mod = 10**9 +7
n, a, b = map(int, input().split())

nb = str(bin(n))[2:]
nblis = []
for k in range(len(nb)):
  if nb[-k-1] == '1':
    nblis.append(k)

two = [2]
for k in range(len(nb)-1):
  two.append(two[-1]*two[-1]%mod)


ans = 1
for item in nblis:
  ans = ans * two[item] %mod



bi = str(bin(mod-2))[2:]
blis = []
for k in range(len(bi)):
  if bi[-k-1] == '1':
    blis.append(k)


def modinv(N):
  if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res

ans_a = 1
for k in range(n-a+1, n+1):
  ans_a = ans_a*k%mod
amother = 1
for k in range(2, a+1):
  amother = amother * k % mod
ans_a = ans_a*modinv(amother)%mod


ans_b = 1
for k in range(n-b+1, n+1):
  ans_b = ans_b*k%mod
bmother = 1
for k in range(2, b+1):
  bmother = bmother * k % mod  
ans_b = ans_b*modinv(bmother)%mod

print((ans-ans_a-ans_b-1)%mod) mod = 10**9 +7 mod 10**9 +7 10**9 10 9 7 n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b nb = str(bin(n))[2:] nb str(bin(n))[2:] (bin(n)) str bin(n) bin n 2: 2 nblis = [] nblis [] for k in range(len(nb)):
  if nb[-k-1] == '1':
    nblis.append(k) k range(len(nb)) range len(nb) len nb if nb[-k-1] == '1':
    nblis.append(k) nb[-k-1] == '1' nb[-k-1] nb -k-1 -k k 1 '1' nblis.append(k) nblis.append nblis append k two = [2] two [2] 2 for k in range(len(nb)-1):
  two.append(two[-1]*two[-1]%mod) k range(len(nb)-1) range len(nb)-1 len(nb) len nb 1 two.append(two[-1]*two[-1]%mod) two.append two append two[-1]*two[-1]%mod two[-1]*two[-1] two[-1] two -1 two[-1] two -1 mod ans = 1 ans 1 for item in nblis:
  ans = ans * two[item] %mod item nblis ans = ans * two[item] %mod ans ans * two[item] %mod ans * two[item] ans two[item] two item mod bi = str(bin(mod-2))[2:] bi str(bin(mod-2))[2:] (bin(mod-2)) str bin(mod-2) bin mod-2 mod 2 2: 2 blis = [] blis [] for k in range(len(bi)):
  if bi[-k-1] == '1':
    blis.append(k) k range(len(bi)) range len(bi) len bi if bi[-k-1] == '1':
    blis.append(k) bi[-k-1] == '1' bi[-k-1] bi -k-1 -k k 1 '1' blis.append(k) blis.append blis append k def modinv(N):
  if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res modinv if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res N == 1 N 1 return 1 1 res = 1 res 1 li = [] li [] for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
     _ range(len(bi)) range len(bi) len bi li.append(N%mod) li.append li append N%mod N mod N = N*N%mod N N*N%mod N*N N N mod for item in blis:
      res = res * li[item] %mod
     item blis res = res * li[item] %mod res res * li[item] %mod res * li[item] res li[item] li item mod return res res N N ans_a = 1 ans_a 1 for k in range(n-a+1, n+1):
  ans_a = ans_a*k%mod k range(n-a+1, n+1) range n-a+1 n-a n a 1 n+1 n 1 ans_a = ans_a*k%mod ans_a ans_a*k%mod ans_a*k ans_a k mod amother = 1 amother 1 for k in range(2, a+1):
  amother = amother * k % mod k range(2, a+1) range 2 a+1 a 1 amother = amother * k % mod amother amother * k % mod amother * k amother k mod ans_a = ans_a*modinv(amother)%mod ans_a ans_a*modinv(amother)%mod ans_a*modinv(amother) ans_a modinv(amother) modinv amother mod ans_b = 1 ans_b 1 for k in range(n-b+1, n+1):
  ans_b = ans_b*k%mod k range(n-b+1, n+1) range n-b+1 n-b n b 1 n+1 n 1 ans_b = ans_b*k%mod ans_b ans_b*k%mod ans_b*k ans_b k mod bmother = 1 bmother 1 for k in range(2, b+1):
  bmother = bmother * k % mod   k range(2, b+1) range 2 b+1 b 1 bmother = bmother * k % mod bmother bmother * k % mod bmother * k bmother k mod ans_b = ans_b*modinv(bmother)%mod ans_b ans_b*modinv(bmother)%mod ans_b*modinv(bmother) ans_b modinv(bmother) modinv bmother mod print((ans-ans_a-ans_b-1)%mod) print (ans-ans_a-ans_b-1)%mod ans-ans_a-ans_b-1 ans-ans_a-ans_b ans-ans_a ans ans_a ans_b 1 mod bmother = 1 1 bmother b = map(int, input().split()) map(int, input().split()) b amother = amother * k % mod amother * k % mod amother a, b = map(int, input().split()) map(int, input().split()) a nblis = [] [] nblis def modinv(N):
  if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res def modinv(N):
  if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res modinv ans_b = ans_b*k%mod ans_b*k%mod ans_b amother = 1 1 amother ans_a = ans_a*modinv(amother)%mod ans_a*modinv(amother)%mod ans_a ans = ans * two[item] %mod ans * two[item] %mod ans n, a, b = map(int, input().split()) map(int, input().split()) n ans = 1 1 ans ans_a = ans_a*k%mod ans_a*k%mod ans_a mod = 10**9 +7 10**9 +7 mod ans_a = 1 1 ans_a ans_b = ans_b*modinv(bmother)%mod ans_b*modinv(bmother)%mod ans_b nb = str(bin(n))[2:] str(bin(n))[2:] nb blis = [] [] blis bi = str(bin(mod-2))[2:] str(bin(mod-2))[2:] bi ans_b = 1 1 ans_b two = [2] [2] two bmother = bmother * k % mod bmother * k % mod bmother
mod = 10**9 +7
n, a, b = map(int, input().split())

nb = str(bin(n))[2:]
nblis = []
for k in range(len(nb)):
  if nb[-k-1] == '1':
    nblis.append(k)

two = [2]
for k in range(len(nb)-1):
  two.append(two[-1]*two[-1]%mod)


ans = 1
for item in nblis:
  ans = ans * two[item] %mod



bi = str(bin(mod-2))[2:]
blis = []
for k in range(len(bi)):
  if bi[-k-1] == '1':
    blis.append(k)


def modinv(N):
  if N == 1:
    return 1
  else:
    res = 1
    li = []
    for _ in range(len(bi)):
      li.append(N%mod)
      N = N*N%mod
    for item in blis:
      res = res * li[item] %mod
    return res

ans_a = 1
for k in range(n-a+1, n+1):
  ans_a = ans_a*k%mod
amother = 1
for k in range(2, a+1):
  amother = amother * k % mod
ans_a = ans_a*modinv(amother)%mod


ans_b = 1
for k in range(n-b+1, n+1):
  ans_b = ans_b*k%mod
bmother = 1
for k in range(2, b+1):
  bmother = bmother * k % mod  
ans_b = ans_b*modinv(bmother)%mod

print((ans-ans_a-ans_b-1)%mod)