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

#define lli long long int
#define REP(i,s,n) for(int i=s;i<n;i++)
#define NUM 2520
#define INF (1LL<<50)
#define DEBUG 0
#define mp(a,b) make_pair(a,b)
#define SORT(V) sort(V.begin(),V.end())
#define PI (3.141592653589794)
#define TO_STRING(VariableName) # VariableName
#define LOG(x) if(DEBUG)cout<<TO_STRING(x)<<"="<<x<<" "<<endl;
#define LOG2(x,y) if(DEBUG)cout<<TO_STRING(x)<<"="<<x<<" "<<TO_STRING(y)<<"="<<y<<endl;
#define LOG3(x,y,z) if(DEBUG)cout<<TO_STRING(x)<<"="<<x<<" "<<TO_STRING(y)<<"="<<y<<" "<<TO_STRING(z)<<"="<<z<<endl;
#define LOG4(w,x,y,z) if(DEBUG)cout<<TO_STRING(w)<<"="<<w<<" "<<TO_STRING(x)<<"="<<x<<" "<<TO_STRING(y)<<"="<<y<<" "<<TO_STRING(z)<<"="<<z<<endl;

template<class T>bool chmax(T & a, const T & b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }

const lli MAX = 2001000;
const lli MOD = 1000000007;

lli fac[MAX], finv[MAX], inv[MAX];
/*use method: COMinit(),COM(x,y)*/
// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (lli i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

 // テーブルを作る前処理、先にやっておく
 void nPr_init() {
   fac[0] = fac[1] = 1;
   finv[0] = finv[1] = 1;
   inv[1] = 1;
   for (int i = 2; i < MAX; i++) {
     fac[i] = fac[i - 1] * i % MOD;
     inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
     finv[i] = finv[i - 1] * inv[i] % MOD;
   }
 }
 
 // nPrを計算する (前処理は忘れないように)
 long long nPr(int n, int r) {
   if (n < 0 || r < 0 || n < r) return 0;
   return fac[n] * finv[n - r] % MOD;
 }

// 二項係数計算
long long COM(lli n, lli k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}



// modint: mod 計算を int を扱うように扱える構造体
template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};


//const int MOD = 1000000007;
using mint = Fp<MOD>;

map<pair<lli,lli>,mint> dp;
map<pair<lli,lli>,mint> posSum;

void func(long long N, long long M){

    mint ans = nPr(M,N)*nPr(M,N);

    for(lli i=1;i<=N;i++){
        mint pos = COM(N,i);
        mint posP = nPr(M-i,N-i);
        mint sum = pos*posP*nPr(M,N);

        LOG4(ans,pos,posP,sum);
        if(i%2)ans = ans - sum;
        else ans = ans + sum;
    }
    cout<<ans<<endl;

}

int main(){
    // cout << fixed << setprecision(5);

    
    COMinit();
    long long N;
    scanf("%lld",&N);
    long long M;
    scanf("%lld",&M);
    func(N,M);
    return 0;
}


Measured memory_bytes: 50648