#include <bits/stdc++.h>
using namespace std;

template<int MAX>
struct Combination {
    vector<long long> _inv, _fac, _ifac;
    const long long MOD;
    Combination(long long mod) : _inv(MAX+1), _fac(MAX+1), _ifac(MAX+1), MOD(mod) { init(); }
    inline void init(long long mod = 0) { init_inv(), init_fac(); }

    inline void init_inv() {
        _inv[0] = 0;
        for (int i = 1; i <= MAX; i++) {
            if (i == 1) _inv[i] = 1;
            else {
                _inv[i] = (MOD - (MOD / i) * _inv[MOD % i]) % MOD;
                if (_inv[i] < 0) _inv[i] += MOD;
            }
        }
    }
    inline void init_fac() {
        _fac[0] = _ifac[0] = 1;
        for (int i = 1; i <= MAX; i++) {
            _fac[i] = _fac[i-1] * i % MOD;
            _ifac[i] = _ifac[i-1] * _inv[i] % MOD;
        }
    }

    inline long long modpow(long long n, long long r) {
        n %= MOD, r %= (MOD-1);
        if (!n) return 0;
        long long ret = 1; long long tmp = n;
        while (r != 0) {
            if (r % 2) ret *= tmp;
            tmp *= tmp; tmp %= MOD; ret %= MOD;
            r /= 2;
        }
        return ret;
    }
    inline const long long invb(int i) { return (i <= MAX) ? _inv[i] : this->modpow(i, MOD-2); }
    inline const long long inv(int i) { return _inv[i]; }
    inline const long long fac(int i) { return _fac[i]; }
    inline const long long ifac(int i) { return _ifac[i]; }

    const long long operator()(int n, int r) {
        if (n < r) return 0;
        return fac(n) * ifac(r) % MOD * ifac(n-r) % MOD;
    }
};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    constexpr int MAX = 300000;
    constexpr int mod = 1000000007;
    Combination<MAX> C(mod);
    long long m, n; cin >> n >> m;
    long long ans = C.modpow(m, n);
    for (int i = 1; i <= m-1; i++) {
        if (i & 1) ans -= C.modpow(m-i, n) * C(m, m-i) % mod;
        else ans += C.modpow(m-i, n) * C(m, m-i) % mod;
    }
    cout << (ans % mod + mod) % mod << "\n";
    return 0;
}