MOD = 10**9 + 7
n, a, b = map(int, input().split())


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


def fact(a, b, MOD):
    res = 1
    for i in range(a, b+1):
        res *= i
        res %= MOD
    return res


def combi(n, k, MOD):
    x = fact(n - k + 1, n, MOD)
    y = fact(1, k, MOD)
    return x * pow(y, MOD - 2, MOD) % MOD
    

def solve():
    ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD)
    print(ans % MOD)
    #print(pow(2, MOD, MOD))


if __name__ == "__main__":
    solve() MOD = 10**9 + 7 MOD 10**9 + 7 10**9 10 9 7 n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b def pow(x, n, MOD):
    res = 1
    while n:
        if n & 1:
            res *= x
            res %= MOD
        x *= x
        x %= MOD
        n >>= 1
    return res     pow res = 1 res 1 while n:
        if n & 1:
            res *= x
            res %= MOD
        x *= x
        x %= MOD
        n >>= 1
     n if n & 1:
            res *= x
            res %= MOD
         n & 1 n 1 res *= x res x res %= MOD res MOD x *= x x x x %= MOD x MOD n >>= 1 n 1 return res res x x n n MOD MOD def fact(a, b, MOD):
    res = 1
    for i in range(a, b+1):
        res *= i
        res %= MOD
    return res fact res = 1 res 1 for i in range(a, b+1):
        res *= i
        res %= MOD
     i range(a, b+1) range a b+1 b 1 res *= i res i res %= MOD res MOD return res res a a b b MOD MOD def combi(n, k, MOD):
    x = fact(n - k + 1, n, MOD)
    y = fact(1, k, MOD)
    return x * pow(y, MOD - 2, MOD) % MOD
     combi x = fact(n - k + 1, n, MOD) x fact(n - k + 1, n, MOD) fact n - k + 1 n - k n k 1 n MOD y = fact(1, k, MOD) y fact(1, k, MOD) fact 1 k MOD return x * pow(y, MOD - 2, MOD) % MOD x * pow(y, MOD - 2, MOD) % MOD x * pow(y, MOD - 2, MOD) x pow(y, MOD - 2, MOD) pow y MOD - 2 MOD 2 MOD MOD n n k k MOD MOD def solve():
    ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD)
    print(ans % MOD)
    #print(pow(2, MOD, MOD)) solve ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD) ans pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD) pow(2, n, MOD) - 1 - combi(n, a, MOD) pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 combi(n, a, MOD) combi n a MOD combi(n, b, MOD) combi n b MOD print(ans % MOD) print ans % MOD ans MOD if __name__ == "__main__":
    solve() __name__ == "__main__" __name__ "__main__" solve() solve a, b = map(int, input().split()) map(int, input().split()) a def fact(a, b, MOD):
    res = 1
    for i in range(a, b+1):
        res *= i
        res %= MOD
    return res def fact(a, b, MOD):
    res = 1
    for i in range(a, b+1):
        res *= i
        res %= MOD
    return res fact def pow(x, n, MOD):
    res = 1
    while n:
        if n & 1:
            res *= x
            res %= MOD
        x *= x
        x %= MOD
        n >>= 1
    return res     def pow(x, n, MOD):
    res = 1
    while n:
        if n & 1:
            res *= x
            res %= MOD
        x *= x
        x %= MOD
        n >>= 1
    return res     pow n, a, b = map(int, input().split()) map(int, input().split()) n def solve():
    ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD)
    print(ans % MOD)
    #print(pow(2, MOD, MOD)) def solve():
    ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD)
    print(ans % MOD)
    #print(pow(2, MOD, MOD)) solve def combi(n, k, MOD):
    x = fact(n - k + 1, n, MOD)
    y = fact(1, k, MOD)
    return x * pow(y, MOD - 2, MOD) % MOD
     def combi(n, k, MOD):
    x = fact(n - k + 1, n, MOD)
    y = fact(1, k, MOD)
    return x * pow(y, MOD - 2, MOD) % MOD
     combi b = map(int, input().split()) map(int, input().split()) b MOD = 10**9 + 7 10**9 + 7 MOD
MOD = 10**9 + 7
n, a, b = map(int, input().split())


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


def fact(a, b, MOD):
    res = 1
    for i in range(a, b+1):
        res *= i
        res %= MOD
    return res


def combi(n, k, MOD):
    x = fact(n - k + 1, n, MOD)
    y = fact(1, k, MOD)
    return x * pow(y, MOD - 2, MOD) % MOD
    

def solve():
    ans = pow(2, n, MOD) - 1 - combi(n, a, MOD) - combi(n, b, MOD)
    print(ans % MOD)
    #print(pow(2, MOD, MOD))


if __name__ == "__main__":
    solve()