import math
n, a, b = map(int, input().split())
mod = 10**9 + 7
s = pow(2, n, mod) - 1
def cal(n, r):
  p = 1
  q = 1
  for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
  return p*pow(q, mod-2, mod)%mod
print((s - cal(n, a) - cal(n, b))%mod) import math math 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 s = pow(2, n, mod) - 1 s pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 def cal(n, r):
  p = 1
  q = 1
  for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
  return p*pow(q, mod-2, mod)%mod cal p = 1 p 1 q = 1 q 1 for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
   i range(r) range r p = p*(n-i)%mod p p*(n-i)%mod p*(n-i) p n-i n i mod q = q*(i+1)%mod q q*(i+1)%mod q*(i+1) q i+1 i 1 mod return p*pow(q, mod-2, mod)%mod p*pow(q, mod-2, mod)%mod p*pow(q, mod-2, mod) p pow(q, mod-2, mod) pow q mod-2 mod 2 mod mod n n r r print((s - cal(n, a) - cal(n, b))%mod) print (s - cal(n, a) - cal(n, b))%mod s - cal(n, a) - cal(n, b) s - cal(n, a) s cal(n, a) cal n a cal(n, b) cal n b mod s = pow(2, n, mod) - 1 pow(2, n, mod) - 1 s def cal(n, r):
  p = 1
  q = 1
  for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
  return p*pow(q, mod-2, mod)%mod def cal(n, r):
  p = 1
  q = 1
  for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
  return p*pow(q, mod-2, mod)%mod cal b = map(int, input().split()) map(int, input().split()) b a, b = map(int, input().split()) map(int, input().split()) a n, a, b = map(int, input().split()) map(int, input().split()) n mod = 10**9 + 7 10**9 + 7 mod
import math
n, a, b = map(int, input().split())
mod = 10**9 + 7
s = pow(2, n, mod) - 1
def cal(n, r):
  p = 1
  q = 1
  for i in range(r):
    p = p*(n-i)%mod
    q = q*(i+1)%mod
  return p*pow(q, mod-2, mod)%mod
print((s - cal(n, a) - cal(n, b))%mod)