#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <algorithm>
#include <bitset>
#include <complex>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include <cassert>
#include <functional>

typedef long long ll;
using namespace std;

#ifndef LOCAL
#define debug(...) ;
#else
#define debug(...) cerr << __LINE__ << " : " << #__VA_ARGS__ << " = " << _tostr(__VA_ARGS__) << endl;

template<typename T>
ostream &operator<<(ostream &out, const vector<T> &v);

template<typename T1, typename T2>
ostream &operator<<(ostream &out, const pair<T1, T2> &p) {
  out << "{" << p.first << ", " << p.second << "}";
  return out;
}

template<typename T>
ostream &operator<<(ostream &out, const vector<T> &v) {
  out << '{';
  for (const T &item : v) out << item << ", ";
  out << "\b\b}";
  return out;
}

void _tostr_rec(ostringstream &oss) {
  oss << "\b\b \b";
}

template<typename Head, typename... Tail>
void _tostr_rec(ostringstream &oss, Head &&head, Tail &&... tail) {
  oss << head << ", ";
  _tostr_rec(oss, forward<Tail>(tail)...);
}

template<typename... T>
string _tostr(T &&... args) {
  ostringstream oss;
  int size = sizeof...(args);
  if (size > 1) oss << "{";
  _tostr_rec(oss, forward<T>(args)...);
  if (size > 1) oss << "}";
  return oss.str();
}
#endif

#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 200010

vector<ll> factmemo, factmemoInv;
ll factmemoMod = -1;

ll factorial(int n, int M) {
  if (factmemoMod == M) return factmemo[n];
  if (n <= 1) return 1;

  ll res = 1;
  for (int i = 1; i <= n; i++) res = res * i % M;
  return res;
}

ll power(ll k, ll n, int M) {
  ll res = 1;
  while (n > 0) {
    if (n & 1) res = res * k % M;
    k = k * k % M;
    n /= 2;
  }
  return res;
}

void initFactorial(int n, int M) {
  factmemo.assign(n + 1, 0);
  factmemoInv.assign(n + 1, 0);
  factmemoMod = M;
  factmemo[0] = 1;
  for (int i = 1; i <= n; i++) factmemo[i] = factmemo[i - 1] * i % M;
  factmemoInv[n] = power(factmemo[n], M - 2, M);
  for (int i = n; i > 0; i--) factmemoInv[i - 1] = factmemoInv[i] * i % M;
}

//nCm nPm nHm (mod M)

/*Combination*/
ll C(int n, int m, int M) {
  if (n < m) return 0;
  if (m == 0 || n == m) return 1;

  if (factmemoMod == M)
    return factmemo[n] * factmemoInv[m] % M * factmemoInv[n - m] % M;

  ll numer = factorial(n, M);
  ll denom = factorial(m, M) * factorial(n - m, M) % M;

  denom = power((int)denom, M - 2, M);

  return numer * denom % M;
}
/*Permutation*/
ll P(int n, int m, int M) {
  if (n < m) return 0;
  if (m == 0) return 1;

  if (factmemoMod == M)
    return factmemo[n] * factmemoInv[n - m] % M;

  ll numer = factorial(n, M);
  ll denom = factorial(n - m, M);

  denom = power((int)denom, M - 2, M);

  return numer * denom % M;
}
/*Combination with Repetitions*/
ll H(int n, int m, int M) {
  if (n == 0 && m == 0) return 1;
  return C(n + m - 1, m, M);
}

int main() {
  int N, M;

  cin >> N >> M;

  ll ans = 0;

  initFactorial((N + M) * 2, mod);

  for (int i = 0; i <= N; i++) {
    ll c = P(M, N, mod) * C(N, i, mod) % mod * P(M - i, N - i, mod) % mod;
    ans += c * (i % 2 ? -1 : 1);
  }

  ans = (ans % mod + mod) % mod;

  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 34320