#!/usr/bin/env python3

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10 ** 7)

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

MOD = 10**9 + 7
# 二項展開より 2**n - 1 - nCa - nCb を MOD 10**9 + 7 で求めればよい


def combination(n, a):
    # nCk = n! / k! (n-k)! のうち、 n!/(n-k)! を計算する
    res = 1
    div = 1
    for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
    res = (res * pow(div, MOD-2, MOD)) % MOD
    return res


count = (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD
print(count) import sys sys read = sys.stdin.buffer.read read sys.stdin.buffer.read sys.stdin.buffer sys.stdin sys stdin buffer read readline = sys.stdin.buffer.readline readline sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline readlines = sys.stdin.buffer.readlines readlines sys.stdin.buffer.readlines sys.stdin.buffer sys.stdin sys stdin buffer readlines sys.setrecursionlimit(10 ** 7) sys.setrecursionlimit sys setrecursionlimit 10 ** 7 10 7 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 combination(n, a):
    # nCk = n! / k! (n-k)! のうち、 n!/(n-k)! を計算する
    res = 1
    div = 1
    for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
    res = (res * pow(div, MOD-2, MOD)) % MOD
    return res combination res = 1 res 1 div = 1 div 1 for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
     i range(a) range a res *= n-i res n-i n i res %= MOD res MOD div *= a - i div a - i a i div %= MOD div MOD res = (res * pow(div, MOD-2, MOD)) % MOD res (res * pow(div, MOD-2, MOD)) % MOD res * pow(div, MOD-2, MOD) res pow(div, MOD-2, MOD) pow div MOD-2 MOD 2 MOD MOD return res res n n a a count = (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD count (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b) pow(2, n, MOD) - 1 - combination(n, a) pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 combination(n, a) combination n a combination(n, b) combination n b MOD print(count) print count readlines = sys.stdin.buffer.readlines sys.stdin.buffer.readlines readlines count = (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD count def combination(n, a):
    # nCk = n! / k! (n-k)! のうち、 n!/(n-k)! を計算する
    res = 1
    div = 1
    for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
    res = (res * pow(div, MOD-2, MOD)) % MOD
    return res def combination(n, a):
    # nCk = n! / k! (n-k)! のうち、 n!/(n-k)! を計算する
    res = 1
    div = 1
    for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
    res = (res * pow(div, MOD-2, MOD)) % MOD
    return res combination readline = sys.stdin.buffer.readline sys.stdin.buffer.readline readline read = sys.stdin.buffer.read sys.stdin.buffer.read read n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a b = map(int, input().split()) map(int, input().split()) b MOD = 10**9 + 7 10**9 + 7 MOD
#!/usr/bin/env python3

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10 ** 7)

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

MOD = 10**9 + 7
# 二項展開より 2**n - 1 - nCa - nCb を MOD 10**9 + 7 で求めればよい


def combination(n, a):
    # nCk = n! / k! (n-k)! のうち、 n!/(n-k)! を計算する
    res = 1
    div = 1
    for i in range(a):
        res *= n-i
        res %= MOD
        div *= a - i
        div %= MOD

    # print(f'n {n}, a {a}, res {res}, div {div}')
    res = (res * pow(div, MOD-2, MOD)) % MOD
    return res


count = (pow(2, n, MOD) - 1 - combination(n, a) - combination(n, b)) % MOD
print(count)
