/* ---------- STL Libraries ---------- */
// IO library
#include <cstdio>

#include <fstream>
#include <iomanip>
#include <ios>
#include <iostream>

// algorithm library
#include <algorithm>

#include <cmath>
#include <numeric>
#include <random>
#include <cstring>
#include <cassert>

// container library
#include <array>
#include <bitset>
#include <deque>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>
#include <stack>

// type
#include <cstdint>
#include <functional>

/* ---------- Namespace ---------- */
using namespace std;

/* ---------- Type ---------- */
using ll = long long;
#define int ll
template <class T> using MaxHeap = priority_queue<T>;
template <class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;
#define P pair<ll, ll>

/* ---------- Constants  */
const double PI = 3.141592653589793238462643383279;
const ll MOD = 1e9 + 7;
const int INF = 1LL << 55;

/* ---------- Functions */
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

/* v-v-v-v-v-v-v-v-v Main Part v-v-v-v-v-v-v-v-v */
class Combination {
    int powmod(int a, int p) {
        int ans = 1;
        int mul = a;

        for (; p > 0; p >>= 1, mul = (mul * mul) % mod) {
            if ((p & 1) == 1) ans = (ans * mul) % mod;
        }

        return ans;
    }
public:
    int N;
    int mod;
    vector<int> fact;
    vector<int> revFact;

    Combination(int n, int m) : N(n), mod(m), fact(n+1), revFact(n+1) {
        fact[0] = 1;
        for (int i = 1; i <= N; i++) {
            fact[i] = fact[i-1] * i;
            fact[i] %= mod;
        }

        // Fermat's little theorem
        revFact[N] = powmod(fact[N], mod - 2);

        for (int i = N-1; i >= 0; i--) {
            revFact[i] = revFact[i+1] * (i+1);
            revFact[i] %= mod;
        }
    }

    int get(int a, int b) {
        if (a < 0 || b < 0) return 0;
        if (b > a) return 0;
        return (((fact[a] * revFact[b]) % mod) * revFact[a-b]) % mod;
    }
};

int powmod(int a, int p, int mod) {
    int ans = 1;
    int mul = a;

    for (; p > 0; p >>= 1, mul = (mul * mul) % mod) {
        if ((p & 1) == 1) ans = (ans * mul) % mod;
    }

    return ans;
}

signed main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int N, M;
    cin >> N >> M;

    auto comb = new Combination(2 * N, MOD);

    int ret= 0;
    for (int k = 0; k < M; k++) {
        int tmp = comb->get(M, k) * powmod(M-k, N, MOD) % MOD;
        if (k % 2 != 0) tmp *= -1;
        ret += MOD + tmp;
        ret %= MOD;
    }

    cout << ret << endl;
    return 0;
}