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

#define FOR(i, n) for (int i = 0; i < int(n); ++i)
#define FO(i, a, b) for (int i = (a); i < int(b); ++i)
#define OF(i, a, b) for (int i = (b)-1; i >= int(a); --i)

#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((b) < (a) ? (a) : (b))

#define REMIN(a, b) ((a) = min(a, b))
#define REMAX(a, b) ((a) = max(a, b))

#define ALL(c) (c).begin(), (c).end()

#define SQR(x) ((x) * (x))

//

const int N = 3009;
int dp[N][N][2];

int main() {
  ios_base::sync_with_stdio(0);

  int n, m;
  const int mod = 1e9 + 7;

  cin >> n >> m;

  dp[0][0][1] = 1;

  FO(i, 1, n + 1) {
    FO(k, 0, i + 1) {
      int r0 = 1LL * dp[i - 1][k][0] * (m - k) % mod;
      if (k - 1 >= 0) r0 = (r0 + 1LL * dp[i - 1][k - 1][1] * (m - k + 1)) % mod;
      dp[i][k][0] = r0;

      dp[i][k][1] = (1LL * dp[i - 1][k][0] + dp[i - 1][k][1]) * k % mod;

      // cerr << "dp[" << i << "][" << k << "][0] == " << dp[i][k][0] << endl;
      // cerr << "dp[" << i << "][" << k << "][1] == " << dp[i][k][1] << endl;
    }
  }

  int r = 0;
  FOR(i, n + 1) r = (r + dp[n][i][1]) % mod;

  cout << r << endl;

  return 0;
}