#include <iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<string>
#include<iostream>
#include<sstream>
#include<set>
#include<map>
#include<queue>
#include<bitset>
#include<vector>
#include<limits.h>
#include<assert.h>
#include <unordered_set>
#include <unordered_map>

#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define FOR(I, A, B) for (int I = (A); I <= (B); ++I)
#define FORS(I, S) for (int I = 0; S[I]; ++I)
#define RS(X) scanf("%s", (X))
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define CASET int ___T; scanf("%d", &___T); for(int cs=1;cs<=___T;cs++)
#define MP make_pair
#define PB push_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define F first
#define S second

using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PII> VPII;
typedef pair<LL,LL> PLL;
typedef vector<PLL> VPLL;
typedef set<LL> SLL;
typedef unordered_set<LL> USLL;
typedef string STR;

template<class T> void _R(T &x) { cin >> x; }
void _R(int &x) { scanf("%d", &x); }
void _R(LL &x) { scanf("%lld", &x); }
void _R(double &x) { scanf("%lf", &x); }
void _R(char &x) { scanf(" %c", &x); }
void _R(char *x) { scanf("%s", x); }
void R() {}
template<class T, class... U> void R(T &head, U &... tail) { _R(head); R(tail...); }
template<class T> void _W(const T &x) { cout << x; }
void _W(const int &x) { printf("%d", x); }
void _W(const LL &x) { printf("%lld", x); }
void _W(const double &x) { printf("%.16f", x); }
void _W(const char &x) { putchar(x); }
void _W(const char *x) { printf("%s", x); }
template<class T,class U> void _W(const pair<T,U> &x) {_W(x.F); putchar(' '); _W(x.S);}
template<class T> void _W(const vector<T> &x) { for (auto i = x.begin(); i != x.end(); _W(*i++)) if (i != x.cbegin()) putchar(' '); }
void W() {}
template<class T, class... U> void W(const T &head, const U &... tail) { _W(head); putchar(sizeof...(tail) ? ' ' : '\n'); W(tail...); }
#ifdef HOME
 #define DEBUG(...) {printf("# ");printf(__VA_ARGS__);puts("");}
#else
 #define DEBUG(...)
#endif
int MOD = 1e9+7;

LL degree(LL elem, LL deg) {
  if (deg == 0) {
    return 1;
  }
  LL tmp = degree(elem, deg / 2);
  if (deg % 2 == 0) {
    return (tmp * tmp) % MOD;
  } else {
    return (((tmp * tmp) % MOD) * elem) % MOD;
  }
}

LL find_reverse_element(LL b) {
  return degree(b, MOD - 2);
}

int main() {
  LL n, m;
  R(n, m);
  std::vector<LL> f(std::max(n, m) + 1);

  f[0] = 1;

  for (LL i = 1; i < (LL)f.size(); ++i) {
    f[i] = (f[i - 1] * (i % MOD)) % MOD;
  }

  // W(f);

  LL res = 0;

  for (LL i = 0; i <= n; ++i) {
    LL b = (((((f[i] * f[n - i]) % MOD) * f[m - i]) % MOD) * ((f[m - n] * f[m - n]) % MOD)) % MOD;
    // std::cout << "calc reverse ..." << std::endl;
    LL b_reverse = find_reverse_element(b);
    // std::cout << "reverse of " << b << " = " << b_reverse << std::endl;
    LL tmp = ((((((f[n] * f[m]) % MOD) * b_reverse) % MOD) * ((f[m - i] * f[m - i]) % MOD)) % MOD);
    if (i % 2 == 0){
      res += tmp;
    } else {
      res += MOD - tmp;
    }
    res %= MOD;
    // std::cout << "res: " << res << std::endl;
  }

  W(res);

  return 0;
}


Measured memory_bytes: 7132