#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstring>
#include <deque>
#include <forward_list>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
typedef long long ll;
typedef pair<int, int> P;
typedef bitset<16> BS;
struct edge {
    int to, cost, id;
};
const ll MOD = 1E+09 + 7; // =998244353;
const ll INF = 1E18;
const int MAX_N = 1E+05;

ll dx[4] = { -1, 1, 0, 0 }, dy[4] = { 0, 0, -1, 1 };

ll N, M;

ll modfac[MAX_N + 1];
ll modfacinv[MAX_N + 1];

ll modPow(ll x, ll a);
ll modfactor(ll p);
void modfactorInv(ll n);

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> N >> M;
    modfactor(M);

    ll ans = 0;
    for (ll i = 0; i <= M; i++) {
        ll res = ((modfac[M] * modfacinv[M - i]) % MOD * modfacinv[i]) % MOD;
        res *= modPow(M - i, N);
        res %= MOD;
        if (i & 1) {
            ans += (-res + MOD) % MOD;
            ans %= MOD;
        } else {
            ans += res;
            ans %= MOD;
        }
    }

    /*
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            cout << "i = " << i << ", j = " << j << ", dp = " << dp[i][j] << "\n";
        }
    }
    */

    cout << ans << "\n";

    return 0;
}

// n!を求める
ll modfactor(ll n)
{
    modfac[0] = 1;
    ll p = 1;
    while (p <= n) {
        //cout << p << "\n";
        modfac[p] = (p * modfac[p - 1]) % MOD;
        p++;
    }
    modfacinv[n] = modPow(modfac[n], MOD - 2);
    modfactorInv(n);
    return modfac[n];
}

// (n!)^-1を求める
void modfactorInv(ll n)
{
    ll p = n - 1;
    while (p >= 0) {
        modfacinv[p] = ((p + 1) * modfacinv[p + 1]) % MOD;
        p--;
    }
}

ll modPow(ll x, ll a)
{
    ll ans = 1;
    while (a > 0) {
        if (a & 1) {
            ans = (ans * x) % MOD;
        }
        x = (x * x) % MOD;
        a >>= 1;
    }
    return ans;
}