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

def comb(N,x):
  numerator = 1
  for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
  denominator = 1
  for j in range(1,x+1):
    denominator = denominator *j%mod
  d = pow(denominator,mod-2,mod)
  return (numerator*d)%mod
al = pow(2,n,mod)-1
ac =comb(n,a)
bc =comb(n,b)
print((al-ac-bc)%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 comb(N,x):
  numerator = 1
  for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
  denominator = 1
  for j in range(1,x+1):
    denominator = denominator *j%mod
  d = pow(denominator,mod-2,mod)
  return (numerator*d)%mod comb numerator = 1 numerator 1 for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
   i range(N-x+1,N+1) range N-x+1 N-x N x 1 N+1 N 1 numerator = numerator *i%mod numerator numerator *i%mod numerator *i numerator i mod denominator = 1 denominator 1 for j in range(1,x+1):
    denominator = denominator *j%mod
   j range(1,x+1) range 1 x+1 x 1 denominator = denominator *j%mod denominator denominator *j%mod denominator *j denominator j mod d = pow(denominator,mod-2,mod) d pow(denominator,mod-2,mod) pow denominator mod-2 mod 2 mod return (numerator*d)%mod (numerator*d)%mod numerator*d numerator d mod N N x x al = pow(2,n,mod)-1 al pow(2,n,mod)-1 pow(2,n,mod) pow 2 n mod 1 ac =comb(n,a) ac comb(n,a) comb n a bc =comb(n,b) bc comb(n,b) comb n b print((al-ac-bc)%mod) print (al-ac-bc)%mod al-ac-bc al-ac al ac bc mod al = pow(2,n,mod)-1 pow(2,n,mod)-1 al n,a,b = map(int,input().split()) map(int,input().split()) n mod = 10**9+7 10**9+7 mod bc =comb(n,b) comb(n,b) bc ac =comb(n,a) comb(n,a) ac b = map(int,input().split()) map(int,input().split()) b a,b = map(int,input().split()) map(int,input().split()) a def comb(N,x):
  numerator = 1
  for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
  denominator = 1
  for j in range(1,x+1):
    denominator = denominator *j%mod
  d = pow(denominator,mod-2,mod)
  return (numerator*d)%mod def comb(N,x):
  numerator = 1
  for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
  denominator = 1
  for j in range(1,x+1):
    denominator = denominator *j%mod
  d = pow(denominator,mod-2,mod)
  return (numerator*d)%mod comb
n,a,b = map(int,input().split())
mod = 10**9+7

def comb(N,x):
  numerator = 1
  for i in range(N-x+1,N+1):
    numerator = numerator *i%mod
  denominator = 1
  for j in range(1,x+1):
    denominator = denominator *j%mod
  d = pow(denominator,mod-2,mod)
  return (numerator*d)%mod
al = pow(2,n,mod)-1
ac =comb(n,a)
bc =comb(n,b)
print((al-ac-bc)%mod)