import functools
N, A, B = map(int, input().split())
MOD = 10 ** 9 + 7

def modpow(x, n):
    ret = 1
    while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
    return ret

@functools.lru_cache(maxsize=None)
def modinv(x):
    return modpow(x, MOD - 2)

def modcomb(n, r):
    ret = 1
    for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
    for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
    return ret

total = modpow(2, N) - 1
ans = total - (modcomb(N, A) + modcomb(N, B))
ans %= MOD
print(ans) import functools functools 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 modpow(x, n):
    ret = 1
    while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
    return ret modpow ret = 1 ret 1 while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
     n if n & 1:
            ret = ret * x % MOD
         n & 1 n 1 ret = ret * x % MOD ret ret * x % MOD ret * x ret x MOD x = x * x % MOD x x * x % MOD x * x x x MOD n >>= 1 n 1 return ret ret x x n n def modinv(x):
    return modpow(x, MOD - 2) modinv return modpow(x, MOD - 2) modpow(x, MOD - 2) modpow x MOD - 2 MOD 2 x x @functools.lru_cache(maxsize=None) modinv maxsize=None @functools.lru_cache(maxsize=None) functools.lru_cache maxsize=None maxsize None modinv def modcomb(n, r):
    ret = 1
    for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
    for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
    return ret modcomb ret = 1 ret 1 for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
     i range(n, n - r, -1) range n n - r n r -1 ret *= i ret i ret %= MOD ret MOD for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
     i range(r, 1, -1) range r 1 -1 ret *= modinv(i) ret modinv(i) modinv i ret %= MOD ret MOD return ret ret n n r r total = modpow(2, N) - 1 total modpow(2, N) - 1 modpow(2, N) modpow 2 N 1 ans = total - (modcomb(N, A) + modcomb(N, B)) ans total - (modcomb(N, A) + modcomb(N, B)) total modcomb(N, A) + modcomb(N, B) modcomb(N, A) modcomb N A modcomb(N, B) modcomb N B ans %= MOD ans MOD print(ans) print ans A, B = map(int, input().split()) map(int, input().split()) A total = modpow(2, N) - 1 modpow(2, N) - 1 total ans %= MOD MOD ans N, A, B = map(int, input().split()) map(int, input().split()) N B = map(int, input().split()) map(int, input().split()) B def modpow(x, n):
    ret = 1
    while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
    return ret def modpow(x, n):
    ret = 1
    while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
    return ret modpow ans = total - (modcomb(N, A) + modcomb(N, B)) total - (modcomb(N, A) + modcomb(N, B)) ans def modcomb(n, r):
    ret = 1
    for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
    for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
    return ret def modcomb(n, r):
    ret = 1
    for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
    for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
    return ret modcomb MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD def modinv(x):
    return modpow(x, MOD - 2) def modinv(x):
    return modpow(x, MOD - 2) modinv
import functools
N, A, B = map(int, input().split())
MOD = 10 ** 9 + 7

def modpow(x, n):
    ret = 1
    while n:
        if n & 1:
            ret = ret * x % MOD
        x = x * x % MOD
        n >>= 1
    return ret

@functools.lru_cache(maxsize=None)
def modinv(x):
    return modpow(x, MOD - 2)

def modcomb(n, r):
    ret = 1
    for i in range(n, n - r, -1):
        ret *= i
        ret %= MOD
    for i in range(r, 1, -1):
        ret *= modinv(i)
        ret %= MOD
    return ret

total = modpow(2, N) - 1
ans = total - (modcomb(N, A) + modcomb(N, B))
ans %= MOD
print(ans)
