n, a, b = map(int, input().split())
mod = 1000000007

def cmb(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
 
a = cmb(n, a)
b = cmb(n, b)

total=(pow(2,n)-(1+a+b))%mod

print(total) n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b mod = 1000000007 mod 1000000007 def cmb(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
  cmb 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 numerator * d numerator d N N x x a = cmb(n, a) a cmb(n, a) cmb n a b = cmb(n, b) b cmb(n, b) cmb n b total=(pow(2,n)-(1+a+b))%mod total (pow(2,n)-(1+a+b))%mod pow(2,n)-(1+a+b) pow(2,n) pow 2 n 1+a+b 1+a 1 a b mod print(total) print total n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a total=(pow(2,n)-(1+a+b))%mod (pow(2,n)-(1+a+b))%mod total b = map(int, input().split()) map(int, input().split()) b a = cmb(n, a) cmb(n, a) a def cmb(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
  def cmb(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
  cmb b = cmb(n, b) cmb(n, b) b mod = 1000000007 1000000007 mod
n, a, b = map(int, input().split())
mod = 1000000007

def cmb(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
 
a = cmb(n, a)
b = cmb(n, b)

total=(pow(2,n)-(1+a+b))%mod

print(total)
