mod = 10**9+7
n,a,b = map(int,input().split())
base = pow(2,n,mod)-1
def comb(n,k):
  comb = 1
  for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
  for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
  return comb
print((base-comb(n,a)-comb(n,b))%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 base = pow(2,n,mod)-1 base pow(2,n,mod)-1 pow(2,n,mod) pow 2 n mod 1 def comb(n,k):
  comb = 1
  for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
  for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
  return comb comb comb = 1 comb 1 for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
   i range(n-k+1,n+1) range n-k+1 n-k n k 1 n+1 n 1 comb *= i comb i comb %= mod comb mod for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
   i range(1, k+1) range 1 k+1 k 1 comb *= pow(i,mod-2,mod) comb pow(i,mod-2,mod) pow i mod-2 mod 2 mod comb %= mod comb mod return comb comb n n k k print((base-comb(n,a)-comb(n,b))%mod) print (base-comb(n,a)-comb(n,b))%mod base-comb(n,a)-comb(n,b) base-comb(n,a) base comb(n,a) comb n a comb(n,b) comb n b mod mod = 10**9+7 10**9+7 mod n,a,b = map(int,input().split()) map(int,input().split()) n b = map(int,input().split()) map(int,input().split()) b a,b = map(int,input().split()) map(int,input().split()) a base = pow(2,n,mod)-1 pow(2,n,mod)-1 base def comb(n,k):
  comb = 1
  for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
  for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
  return comb def comb(n,k):
  comb = 1
  for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
  for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
  return comb comb
mod = 10**9+7
n,a,b = map(int,input().split())
base = pow(2,n,mod)-1
def comb(n,k):
  comb = 1
  for i in range(n-k+1,n+1):
    comb *= i
    comb %= mod
  for i in range(1, k+1):
    comb *= pow(i,mod-2,mod)
    comb %= mod
  return comb
print((base-comb(n,a)-comb(n,b))%mod)