We have two distinct integers A and B.
Print the integer K such that |A - K| = |B - K|.
If such an integer does not exist, print IMPOSSIBLE instead.

-----Constraints-----
 - All values in input are integers.
 - 0 \leq A,\ B \leq 10^9
 - A and B are distinct.

-----Input-----
Input is given from Standard Input in the following format:
A B

-----Output-----
Print the integer K satisfying the condition.
If such an integer does not exist, print IMPOSSIBLE instead.

-----Sample Input-----
2 16

-----Sample Output-----
9

|2 - 9| = 7 and |16 - 9| = 7, so 9 satisfies the condition.
[{"code": "A, B = map(int, input().split())\n \nif (A+B) %2 == 0: print((A+B) // 2)\nelse: print('IMPOSSIBLE')", "passed": true, "time": 1.87, "memory": 14320.0, "status": "done"}, {"code": "import bisect, collections, copy, heapq, itertools, math, string, sys\ninput = lambda: sys.stdin.readline().rstrip() \nsys.setrecursionlimit(10**7)\nINF = float('inf')\ndef I(): return int(input())\ndef F(): return float(input())\ndef SS(): return input()\ndef LI(): return [int(x) for x in input().split()]\ndef LI_(): return [int(x)-1 for x in input().split()]\ndef LF(): return [float(x) for x in input().split()]\ndef LSS(): return input().split()\n\ndef resolve():\n    A, B = LI()\n\n    if (A - B) % 2 == 0:\n        print(((A + B) // 2))\n    else:\n        print('IMPOSSIBLE')\n\ndef __starting_point():\n    resolve()\n\n__starting_point()", "passed": true, "time": 1.63, "memory": 14136.0, "status": "done"}, {"code": "A,B=map(int,input().split())\nK=(A**2-B**2)/(2*(A-B))\nif K%1==0:\n  print(int(K))\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.21, "memory": 14112.0, "status": "done"}, {"code": "A,B=map(int,input().split())\nprint((A+B)//2) if (A+B)%2==0 else print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14120.0, "status": "done"}, {"code": "A,B=map(int,input().split())\nprint((A+B)//2 if (A+B)%2==0 else \"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14132.0, "status": "done"}, {"code": "# A\na, b = map(int,input().split())\nk=max(a,b)-(max(a,b)-min(a,b))/2\nif k.is_integer():\n    print(int(k))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.16, "memory": 14232.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nif (A + B) % 2 == 0:\n    print(int((A + B) / 2))\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14348.0, "status": "done"}, {"code": "a = list(map(int,input().split()))\nA = a[0]\nB = a[1]\n\nif (A+B) % 2 == 0:\n    print(((A+B)//2))\nelse:\n    print('IMPOSSIBLE')\n", "passed": true, "time": 0.16, "memory": 14104.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nprint(\"IMPOSSIBLE\" if a%2 != b%2 else (a+b)//2)", "passed": true, "time": 0.23, "memory": 14124.0, "status": "done"}, {"code": "a,b=map(int, input().split())\n\nif (a+b)%2==0:\n    print((a+b)//2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 1.71, "memory": 14264.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif a % 2 == 0 and b % 2 == 1:\n    print('IMPOSSIBLE')\nelif a % 2 == 1 and b % 2 == 0:\n    print('IMPOSSIBLE')\nelse:\n    print((a+b)//2)", "passed": true, "time": 0.23, "memory": 14272.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif abs(a-b) % 2 == 0:\n    print((a+b)//2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14296.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nk = (a * a - b * b) / (2 * a - 2 * b)\nif k == int(k):\n    print(int(k))\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14352.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nif (A - B) % 2 != 0:\n    K = 'IMPOSSIBLE'\nelse:\n    K = (A + B) // 2\n\nprint(K)", "passed": true, "time": 0.14, "memory": 14232.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nk = (a + b)//2\nif a + b == 2 * k:\n    print(k)\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.23, "memory": 14240.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n\nif a == - b :\n    print('IMPOSSIBLE')\nelif (a+b)//2 != (a+b)/2:\n    print('IMPOSSIBLE')\nelse:\n    print(((a+b)//2))\n", "passed": true, "time": 0.14, "memory": 14228.0, "status": "done"}, {"code": "A,B = map(int,input().split())\n\nif (A + B) % 2 == 0:\n    print((A+B) // 2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14228.0, "status": "done"}, {"code": "a, b = list(map(int, input().split( )))\ns = a + b\nif s %2 ==1:\n  print('IMPOSSIBLE')\nelse:\n  print((s//2))\n", "passed": true, "time": 0.14, "memory": 14128.0, "status": "done"}, {"code": "a,b = [int(v) for v in input().split()]\nif abs(a-b) % 2 == 0:\n    print((int((max(a,b)+min(a,b))/2)))\nelse:\n    print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.14, "memory": 14132.0, "status": "done"}, {"code": "a,b=map(int,input().split())\n\nif (a+b)%2==0:\n    print(int((a+b)/2))\nelse :\n    print('IMPOSSIBLE')", "passed": true, "time": 0.15, "memory": 14228.0, "status": "done"}, {"code": "A,B=map(int,input().split())\nif A>B:\n  if (A-B)%2==0:\n    print(B+(A-B)//2)\n  else:\n    print(\"IMPOSSIBLE\")\nelse:\n  if (B-A)%2==0:\n    print(A+(B-A)//2)\n  else:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14292.0, "status": "done"}, {"code": "def resolve():\n    a,b = map(int,input().split())\n    if a%2 != b%2:\n        print('IMPOSSIBLE')\n    else:\n        print((a+b)//2)\nresolve()", "passed": true, "time": 0.14, "memory": 14252.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a+b)%2==0:\n    print((a+b)//2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14324.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nif (A+B)%2 != 0:\n    print(\"IMPOSSIBLE\")\nelse:\n    K = int((A+B)/2)\n    print(K)", "passed": true, "time": 0.14, "memory": 14112.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n# a - k = -b + k or b - k\n# a + b == 2k or a - b = 0\nif a == b:\n    print((0))\nelif (a + b) % 2 == 0:\n    print(((a + b) // 2))\nelse:\n    print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.14, "memory": 14312.0, "status": "done"}, {"code": "a,b= map(int,input().split())\nif (b+a)%2==0:\n  print((a+b)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14128.0, "status": "done"}, {"code": "A, B = map(int, input().split())\nprint((A + B) // 2 if (A + B) % 2 == 0 else \"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14252.0, "status": "done"}, {"code": "A, B = map(int, input().split())\nprint (\"IMPOSSIBLE\" if (A+B) % 2 > 0 else (A+B)//2)", "passed": true, "time": 0.23, "memory": 14336.0, "status": "done"}, {"code": "a, b = list(map(int,input().split()))\nif (a + b) % 2 == 0:\n  print(((a + b)//2))\nelse:\n  print('IMPOSSIBLE')\n", "passed": true, "time": 0.55, "memory": 14336.0, "status": "done"}, {"code": "a,b=map(int, input().split())\nprint(abs(min(a,b)+abs(a-b)//2) if (a-b)%2==0 else \"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14348.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (b-a)/2%1==0:\n    s=a+(b-a)//2\nelse:\n    s=\"IMPOSSIBLE\"\nprint(s)", "passed": true, "time": 0.14, "memory": 14168.0, "status": "done"}, {"code": "A,B=map(int,input().split(' '))\nif (A+B)%2!=0:\n    print(\"IMPOSSIBLE\")\nelse:\n    print((A+B)//2)", "passed": true, "time": 0.15, "memory": 14376.0, "status": "done"}, {"code": "a,b=list(map(int, input().split()))\nprint(((a+b)//2 if (a+b)%2==0 else 'IMPOSSIBLE'))\n", "passed": true, "time": 0.3, "memory": 14136.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a+b)%2==0:\n  print((a+b)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 1.22, "memory": 14136.0, "status": "done"}, {"code": "A,B = map(int,input().split())\n\nif A%2 != B%2:\n    print('IMPOSSIBLE')\nelse:\n    print(int(abs(A+B)/2))", "passed": true, "time": 0.15, "memory": 14276.0, "status": "done"}, {"code": "A,B=list(map(int,input().split()))\nif abs(A-B)%2==0:\n    print(((A+B)//2))\nelse:\n    print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.15, "memory": 14228.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nprint((a+b)//2 if (a+b)%2==0 else \"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14100.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nprint((a + b) // 2 if (a + b) % 2  == 0 else 'IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14364.0, "status": "done"}, {"code": "A, B = map(int, input().split())\nK = A+B\nif K%2:\n    print('IMPOSSIBLE')\nelse:\n    print(K//2)", "passed": true, "time": 0.14, "memory": 14284.0, "status": "done"}, {"code": "A,B=map(int,input().split())\n\nif (A+B)%2==0:\n    print(int((A+B)/2))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14340.0, "status": "done"}, {"code": "A, B = list(map(int, input().split()))\nK = A + B\n\nif K%2 == 0:\n  print((K//2))\nelse:\n  print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.14, "memory": 14168.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a+b)%2==0:\n  print((a+b)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14104.0, "status": "done"}, {"code": "A, B = list(map(int, input().split()))\nif A > B:\n    A, B = B, A\ndiff = B - A\nif diff % 2:\n    print(\"IMPOSSIBLE\")\nelse:\n    print((A + diff // 2))\n\n", "passed": true, "time": 0.14, "memory": 14224.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nif (A + B) & 1 == 1:\n    print('IMPOSSIBLE')\nelse:\n    print((A + B) // 2)", "passed": true, "time": 0.14, "memory": 14280.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nans=(a+b)//2\nif a%2!=b%2:\n  ans='IMPOSSIBLE'\nprint(ans)", "passed": true, "time": 0.14, "memory": 14388.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nif (a+b) % 2 == 0:\n  print((a+b)//2)\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14136.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nif (a - b) % 2 == 0:\n    print(int((a+b)/2))\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14236.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n\nif (a+b) % 2 == 0:\n    print((int((a+b)//2)))\nelse:\n    print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.16, "memory": 14116.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\nc = (max(a, b)-min(a, b))/2\nif c == int(c):\n    print((int(min(a, b)+c)))\nelse:\n    print('IMPOSSIBLE')\n", "passed": true, "time": 0.14, "memory": 14252.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nx=abs(b+a)\nif(x%2!=0):\n    print(\"IMPOSSIBLE\")\nelse:\n    print(int(x/2))", "passed": true, "time": 0.14, "memory": 14196.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nk = (A + B) / 2\nprint(int(k)) if k.is_integer() else print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14324.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nif((a+b)%2 == 0):\n  print((a+b)//2)\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14348.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif (a + b) % 2 == 0:\n    print((a + b) // 2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14160.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a-b)%2==0:\n  print((a+b)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14136.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a+b)%2==0:\n  print((a+b)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14156.0, "status": "done"}, {"code": "A, B = [int(n) for n in input().split()]\nprint((A+B)//2 if (A+B)%2==0 else 'IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14312.0, "status": "done"}, {"code": "#ABC135 A\n\nA,B = map(int,input().split())\nif (A+B)/2 % 1 == 0:\n    print(int((A+B)/2))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.24, "memory": 14156.0, "status": "done"}, {"code": "A, B = map(int, input().split())\nif (A + B) % 2 != 0:\n  print(\"IMPOSSIBLE\")\nelse:\n  print(int((A+B)/2))", "passed": true, "time": 0.22, "memory": 14228.0, "status": "done"}, {"code": "def LI():\n    return list(map(int, input().split()))\n\n\nA, B = LI()\nif (A+B) % 2 == 0:\n    ans = (A+B)//2\nelse:\n    ans = \"IMPOSSIBLE\"\nprint(ans)\n", "passed": true, "time": 0.23, "memory": 14344.0, "status": "done"}, {"code": "A, B = map(int, input().split())\nif abs(A+B)%2 == 0:\n  print(abs(A+B)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14168.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif (a+b) % 2 == 0:\n    print((a+b)//2)\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.25, "memory": 14268.0, "status": "done"}, {"code": "a,b = list(map(int,input().split()))\nif (abs(a+b))%2 == 0:\n  print((abs(a+b)//2))\nelse:\n  print('IMPOSSIBLE')\n", "passed": true, "time": 0.26, "memory": 14160.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nx=(a+b)/2\nif x.is_integer():\n    print(int(x))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.16, "memory": 14204.0, "status": "done"}, {"code": "import sys\nimport itertools\ntokens = itertools.chain.from_iterable(list(map(str.split, sys.stdin)))\n\nno = 'IMPOSSIBLE'\na = int(next(tokens))\nb = int(next(tokens))\n\n# k = (a^2 - b^2) / {2 (a - b)}\nk = (a**2 - b**2) // (2 * (a - b))\nif abs(a - k) != abs(b - k):\n    print(no)\nelse:\n    print(k)\n", "passed": true, "time": 0.14, "memory": 14320.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n\nif abs(a + b) % 2 == 0:\n    print((abs(a + b) // 2))\nelse:\n    print('IMPOSSIBLE')\n", "passed": true, "time": 0.15, "memory": 14288.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nprint('IMPOSSIBLE' if (a ^ b) & 1 else (a + b) >> 1)", "passed": true, "time": 0.15, "memory": 14256.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nprint((a+b)//2 if (a+b)%2==0 else \"IMPOSSIBLE\")", "passed": true, "time": 0.16, "memory": 14352.0, "status": "done"}, {"code": "a,b=map(int,input().split());print(['IMPOSSIBLE',a+(b-a)//2][(b-a)%2==0])", "passed": true, "time": 0.15, "memory": 14292.0, "status": "done"}, {"code": "a, b = map(int,input().split())\nif (a > b):\n  a, b = b, a\nif ((b - a)%2 == 0):\n  print(a + (b - a)//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.16, "memory": 14204.0, "status": "done"}, {"code": "a=sorted(list(map(int,input().split())))\nif a[1]%2==a[0]%2:\n  print(a[0]+(a[1]-a[0])//2)\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.15, "memory": 14276.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif abs(a-b)%2==0:\n  print((a+b)//2)\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14280.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n\nk = int((a + b) / 2)\nif abs(a - k) == abs(b - k):\n    print(k)\nelse:\n    print(\"IMPOSSIBLE\")\n", "passed": true, "time": 0.14, "memory": 14228.0, "status": "done"}, {"code": "A,B=map(int, input().split())\n\nif (A+B)%2==0:\n\tprint(int((A+B)/2))\nelse:\n\tprint(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14136.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif (a + b) % 2 == 0:\n    print((a + b) // 2)\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.23, "memory": 14120.0, "status": "done"}, {"code": "a, b = map(int,input().split())\nif (a + b) % 2 == 0:\n    print((a + b) // 2)\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14120.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nprint((a+b)//2 if (a+b)%2==0 else 'IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14368.0, "status": "done"}, {"code": "A, B = list(map(int, input().split()))\nif A > B: A, B = B, A\nif (B - A) & 1:\n    print('IMPOSSIBLE')\n    return\nprint((A + (B - A) // 2))\n", "passed": true, "time": 0.14, "memory": 14280.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\n\nif (a+b) % 2 == 0:\n    print(int((a+b)//2))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.15, "memory": 14344.0, "status": "done"}, {"code": "A,B=map(int,input().split())\nx=(A**2-B**2)/(2*(A-B))\nif x%1==0:\n    print(int(x))\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.16, "memory": 14108.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nprint((a+b)//2 if (a+b)%2 == 0 else 'IMPOSSIBLE')", "passed": true, "time": 0.15, "memory": 14368.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\nif (a - b) % 2 == 0:\n    print(((a + b) // 2))\nelse:\n    print('IMPOSSIBLE')\n", "passed": true, "time": 0.14, "memory": 14100.0, "status": "done"}, {"code": "A,B = map(int,input().split())\nif abs(A-B) % 2 == 0:\n    print(min(A,B) + abs(A-B)//2)\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14288.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nif (a + b) % 2 == 0: print((a + b) // 2)\nelse: print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14100.0, "status": "done"}, {"code": "a= list(map(int,input().split()))\nif (a[0]+a[1]) % 2 == 0:\n  print((a[0]+a[1])//2)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.23, "memory": 14212.0, "status": "done"}, {"code": "A,B = map(int,input().split())\nif(abs(A-B) % 2 == 1):\n    print(\"IMPOSSIBLE\")\nelse:\n    print((abs(A-B)//2) + min(A,B))", "passed": true, "time": 0.24, "memory": 14116.0, "status": "done"}, {"code": "A,B=map(int, input().split())\n \nif (A+B)%2==0:\n\tprint(int((A+B)/2))\nelse:\n\tprint(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14132.0, "status": "done"}, {"code": "a,b=map(int,input().split())\nif (a+b)%2 == 0 :\n  print(int((a+b)/2))\nelse :\n  print('IMPOSSIBLE')", "passed": true, "time": 0.23, "memory": 14124.0, "status": "done"}, {"code": "A,B = list(map(int, input().split()))\nprint(((A+B) // 2 if (A+B) % 2 == 0\n             else 'IMPOSSIBLE'))\n", "passed": true, "time": 0.23, "memory": 14364.0, "status": "done"}, {"code": "a,b = map(int,input().split())\n\nif (a + b) % 2 == 0 :\n  print((a+b)//2)\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14240.0, "status": "done"}, {"code": "a, b = list(map(int, input().split()))\nif (a + b) % 2 == 0:\n    print((int((a + b) / 2)))\nelse:\n    print('IMPOSSIBLE')\n", "passed": true, "time": 0.14, "memory": 14316.0, "status": "done"}, {"code": "a,b = map(int,input().split())\nprint(\"IMPOSSIBLE\" if (a+b)%2!=0 else (a+b)//2)", "passed": true, "time": 0.14, "memory": 14272.0, "status": "done"}, {"code": "a, b = [int(i) for i in input().split()]\nif (a + b) % 2 == 0:\n  print(int(abs(a + b) / 2))\nelse:\n  print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14140.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nans = (a**2-b**2)/(2*(a-b))\n\nif ans.is_integer():\n    print(int(ans))\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14352.0, "status": "done"}, {"code": "a, b = map(int, input().split(' '))\nif (a - b) % 2 == 1:\n    print('IMPOSSIBLE')\nelse:\n    print((a + b) // 2)", "passed": true, "time": 0.14, "memory": 14232.0, "status": "done"}, {"code": "A,B =map(int,input().split())\nif (A+B) % 2 == 0:\n    print((A+B)//2)\nelse:\n    print('IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14368.0, "status": "done"}, {"code": "a, b = map(int, input().split())\nprint((a + b) // 2 if (a + b) % 2 == 0 else 'IMPOSSIBLE')", "passed": true, "time": 0.14, "memory": 14296.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nif (A+B)%2 == 0:\n    print(int((A+B)/2))\nelse:\n    print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14136.0, "status": "done"}, {"code": "A, B = map(int, input().split())\n\nK = (A+B) // 2\nif (A+B)%2 == 0:\n  print(K)\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14108.0, "status": "done"}, {"code": "A, B = map(int,input().split())\nif (A + B) % 2 == 0:\n  print(int((A + B) / 2))\nelse:\n  print(\"IMPOSSIBLE\")", "passed": true, "time": 0.14, "memory": 14324.0, "status": "done"}]