import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    N, a, b = map(int, readline().split())

    ans = pow(2, N, MOD) - 1
    ans %= MOD

    def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

    ans -= comb_mod(N, a)
    ans -= comb_mod(N, b)
    ans %= MOD

    print(ans)


if __name__ == '__main__':
    main() import sys sys readline = sys.stdin.readline readline sys.stdin.readline sys.stdin sys stdin readline MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 INF = float('INF') INF float('INF') float 'INF' sys.setrecursionlimit(10 ** 5) sys.setrecursionlimit sys setrecursionlimit 10 ** 5 10 5 def main():
    N, a, b = map(int, readline().split())

    ans = pow(2, N, MOD) - 1
    ans %= MOD

    def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

    ans -= comb_mod(N, a)
    ans -= comb_mod(N, b)
    ans %= MOD

    print(ans) main N, a, b = map(int, readline().split()) N map(int, readline().split()) map int readline().split() ().split () readline split a b ans = pow(2, N, MOD) - 1 ans pow(2, N, MOD) - 1 pow(2, N, MOD) pow 2 N MOD 1 ans %= MOD ans MOD def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

     comb_mod res = 1 res 1 r = min(n - r, r) r min(n - r, r) min n - r n r r for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

         i range(r) range r res *= (n - i) res n - i n i res %= MOD res MOD res *= pow((r - i), MOD - 2, MOD) res pow((r - i), MOD - 2, MOD) pow r - i r i MOD - 2 MOD 2 MOD return res res n n r r ans -= comb_mod(N, a) ans comb_mod(N, a) comb_mod N a ans -= comb_mod(N, b) ans comb_mod(N, b) comb_mod N b ans %= MOD ans MOD print(ans) print ans if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    N, a, b = map(int, readline().split())

    ans = pow(2, N, MOD) - 1
    ans %= MOD

    def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

    ans -= comb_mod(N, a)
    ans -= comb_mod(N, b)
    ans %= MOD

    print(ans) def main():
    N, a, b = map(int, readline().split())

    ans = pow(2, N, MOD) - 1
    ans %= MOD

    def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

    ans -= comb_mod(N, a)
    ans -= comb_mod(N, b)
    ans %= MOD

    print(ans) main MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD INF = float('INF') float('INF') INF readline = sys.stdin.readline sys.stdin.readline readline
import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    N, a, b = map(int, readline().split())

    ans = pow(2, N, MOD) - 1
    ans %= MOD

    def comb_mod(n, r):
        res = 1
        r = min(n - r, r)

        for i in range(r):
            res *= (n - i)
            res %= MOD
            res *= pow((r - i), MOD - 2, MOD)

        return res

    ans -= comb_mod(N, a)
    ans -= comb_mod(N, b)
    ans %= MOD

    print(ans)


if __name__ == '__main__':
    main()
