from math import factorial
ni = lambda: int(input())
nm = lambda: map(int, input().split())
nl = lambda: list(map(int, input().split()))

n,a,b = nm()
mod = 10**9+7

MAX = 10**6


def modpow(a,n,mod):
  res = 1
  while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
  return res
    

ans = modpow(2,n,mod) - 1

def modcom(n,a,mod):
  X=1
  Y=1
  for i in range(a):
    X*=(n-i)
    X%=mod
  for i in range(a):
    Y*=(a-i)
    Y%=mod
  return X * modpow(Y,mod-2,mod)%mod


ans -= modcom(n,a,mod)
ans -= modcom(n,b,mod)

print(ans % mod) from math import factorial ni = lambda: int(input()) ni lambda: int(input()) int(input()) int input() input nm = lambda: map(int, input().split()) nm lambda: map(int, input().split()) map(int, input().split()) map int input().split() ().split () input split nl = lambda: list(map(int, input().split())) nl lambda: list(map(int, input().split())) list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split n,a,b = nm() n nm() nm a b mod = 10**9+7 mod 10**9+7 10**9 10 9 7 MAX = 10**6 MAX 10**6 10 6 def modpow(a,n,mod):
  res = 1
  while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
  return res
     modpow res = 1 res 1 while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
   n>0 n 0 if n&1:
      res = res * a % mod
     n&1 n 1 res = res * a % mod res res * a % mod res * a res a mod a = a * a % mod a a * a % mod a * a a a mod n>>=1 n 1 return res res a a n n mod mod ans = modpow(2,n,mod) - 1 ans modpow(2,n,mod) - 1 modpow(2,n,mod) modpow 2 n mod 1 def modcom(n,a,mod):
  X=1
  Y=1
  for i in range(a):
    X*=(n-i)
    X%=mod
  for i in range(a):
    Y*=(a-i)
    Y%=mod
  return X * modpow(Y,mod-2,mod)%mod modcom X=1 X 1 Y=1 Y 1 for i in range(a):
    X*=(n-i)
    X%=mod
   i range(a) range a X*=(n-i) X n-i n i X%=mod X mod for i in range(a):
    Y*=(a-i)
    Y%=mod
   i range(a) range a Y*=(a-i) Y a-i a i Y%=mod Y mod return X * modpow(Y,mod-2,mod)%mod X * modpow(Y,mod-2,mod)%mod X * modpow(Y,mod-2,mod) X modpow(Y,mod-2,mod) modpow Y mod-2 mod 2 mod mod n n a a mod mod ans -= modcom(n,a,mod) ans modcom(n,a,mod) modcom n a mod ans -= modcom(n,b,mod) ans modcom(n,b,mod) modcom n b mod print(ans % mod) print ans % mod ans mod def modpow(a,n,mod):
  res = 1
  while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
  return res
     def modpow(a,n,mod):
  res = 1
  while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
  return res
     modpow nl = lambda: list(map(int, input().split())) lambda: list(map(int, input().split())) nl def modcom(n,a,mod):
  X=1
  Y=1
  for i in range(a):
    X*=(n-i)
    X%=mod
  for i in range(a):
    Y*=(a-i)
    Y%=mod
  return X * modpow(Y,mod-2,mod)%mod def modcom(n,a,mod):
  X=1
  Y=1
  for i in range(a):
    X*=(n-i)
    X%=mod
  for i in range(a):
    Y*=(a-i)
    Y%=mod
  return X * modpow(Y,mod-2,mod)%mod modcom MAX = 10**6 10**6 MAX nm = lambda: map(int, input().split()) lambda: map(int, input().split()) nm ans -= modcom(n,a,mod) modcom(n,a,mod) ans n,a,b = nm() nm() n ans = modpow(2,n,mod) - 1 modpow(2,n,mod) - 1 ans ni = lambda: int(input()) lambda: int(input()) ni a,b = nm() nm() a mod = 10**9+7 10**9+7 mod ans -= modcom(n,b,mod) modcom(n,b,mod) ans b = nm() nm() b
from math import factorial
ni = lambda: int(input())
nm = lambda: map(int, input().split())
nl = lambda: list(map(int, input().split()))

n,a,b = nm()
mod = 10**9+7

MAX = 10**6


def modpow(a,n,mod):
  res = 1
  while n>0:
    if n&1:
      res = res * a % mod
    a = a * a % mod
    n>>=1
  return res
    

ans = modpow(2,n,mod) - 1

def modcom(n,a,mod):
  X=1
  Y=1
  for i in range(a):
    X*=(n-i)
    X%=mod
  for i in range(a):
    Y*=(a-i)
    Y%=mod
  return X * modpow(Y,mod-2,mod)%mod


ans -= modcom(n,a,mod)
ans -= modcom(n,b,mod)

print(ans % mod)