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

def pow(x, n):
  ans = 1
  while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
  return ans

N=pow(2,n)
def comb(c,d):
  x=1
  for i in range(d):
    x=x*(c-i)%mod
  y=1
  for i in range(d):
    y=y*(i+1)%mod
  return x*pow(y,mod-2)%mod
A=comb(n,a)
B=comb(n,b)
print((N-A-B-1)%mod) n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b mod=10**9+7 mod 10**9+7 10**9 10 9 7 def pow(x, n):
  ans = 1
  while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
  return ans pow ans = 1 ans 1 while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
   n > 0 n 0 if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
     bin(n & 1) == bin(1) bin(n & 1) bin n & 1 n 1 bin(1) bin 1 ans = ans*x%mod ans ans*x%mod ans*x ans x mod x = x*x%mod x x*x%mod x*x x x mod n = n >> 1 n n >> 1 n 1 return ans ans x x n n N=pow(2,n) N pow(2,n) pow 2 n def comb(c,d):
  x=1
  for i in range(d):
    x=x*(c-i)%mod
  y=1
  for i in range(d):
    y=y*(i+1)%mod
  return x*pow(y,mod-2)%mod comb x=1 x 1 for i in range(d):
    x=x*(c-i)%mod
   i range(d) range d x=x*(c-i)%mod x x*(c-i)%mod x*(c-i) x c-i c i mod y=1 y 1 for i in range(d):
    y=y*(i+1)%mod
   i range(d) range d y=y*(i+1)%mod y y*(i+1)%mod y*(i+1) y i+1 i 1 mod return x*pow(y,mod-2)%mod x*pow(y,mod-2)%mod x*pow(y,mod-2) x pow(y,mod-2) pow y mod-2 mod 2 mod c c d d A=comb(n,a) A comb(n,a) comb n a B=comb(n,b) B comb(n,b) comb n b print((N-A-B-1)%mod) print (N-A-B-1)%mod N-A-B-1 N-A-B N-A N A B 1 mod a,b=map(int,input().split()) map(int,input().split()) a 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 B=comb(n,b) comb(n,b) B def pow(x, n):
  ans = 1
  while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
  return ans def pow(x, n):
  ans = 1
  while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
  return ans pow N=pow(2,n) pow(2,n) N def comb(c,d):
  x=1
  for i in range(d):
    x=x*(c-i)%mod
  y=1
  for i in range(d):
    y=y*(i+1)%mod
  return x*pow(y,mod-2)%mod def comb(c,d):
  x=1
  for i in range(d):
    x=x*(c-i)%mod
  y=1
  for i in range(d):
    y=y*(i+1)%mod
  return x*pow(y,mod-2)%mod comb A=comb(n,a) comb(n,a) A
n,a,b=map(int,input().split())
mod=10**9+7

def pow(x, n):
  ans = 1
  while(n > 0):
    if(bin(n & 1) == bin(1)):
      ans = ans*x%mod
    x = x*x%mod
    n = n >> 1 
  return ans

N=pow(2,n)
def comb(c,d):
  x=1
  for i in range(d):
    x=x*(c-i)%mod
  y=1
  for i in range(d):
    y=y*(i+1)%mod
  return x*pow(y,mod-2)%mod
A=comb(n,a)
B=comb(n,b)
print((N-A-B-1)%mod)