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#include <bits/stdc++.h>
#define ll long long
#define debug if(0)

const int MAX_N = 3000;
int n;
ll m;
const ll MOD = 1e9+7;

ll good[MAX_N+3][MAX_N+3];
ll bad[MAX_N+3][MAX_N+3];

int main() {
    std::ios_base::sync_with_stdio(0); std::cin.tie(NULL);

    std::cin >> n >> m;

    int diff = std::max(m-n, (ll)(0));

    /* baza dla n = 1 */
    bad[1][m-1 - diff] = m;
    
    for (int i = 2; i <= n; i++) {
        for (ll k = diff; k <= m; k++) {
            good[i][k - diff] = ((good[i-1][k - diff] + bad[i-1][k - diff]) * (m-k)) % MOD;
            bad[i][k - diff] = bad[i-1][k - diff] * k % MOD;
            if (k+1 <= m)
                bad[i][k - diff] = (bad[i][k - diff] + ((good[i-1][k + 1 - diff] * (k+1) % MOD)) % MOD);
            
            debug {
                std::cout << "good[" << i << "][" << k << "] = " << good[i][k-diff] << "\n";
                std::cout << "bad[" << i << "][" << k << "] = " << bad[i][k-diff] << "\n";
            }
        }
    }

    ll res = 0;
    for (int k = diff; k <= m; k++)
        res = (res + good[n][k - diff]) % MOD;
    std::cout << res << "\n";
}