a, b = [int(x) for x in input().split()]

b = b * 2

print(max(0, a - b)) int(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() int(x) int x a, b = [int(x) for x in input().split()] a [int(x) for x in input().split()] b b = b * 2 b b * 2 b 2 print(max(0, a - b)) print max(0, a - b) max 0 a - b a b b = [int(x) for x in input().split()] [int(x) for x in input().split()] b a, b = [int(x) for x in input().split()] [int(x) for x in input().split()] a b = b * 2 b * 2 b
a, b = [int(x) for x in input().split()]

b = b * 2

print(max(0, a - b))