///////////////////// author : TrEbLeCleF /////////////////////
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<pii> vpii;

#define pb(x) push_back(x)
#define deb(x) cerr <<#x<<" = "<<x<<"\n"
#define print(v,s,e) for(int i = s; i < e; i++)cout << v[i]<<" ";cout<<"\n";
#define INF 1e17
#define PI 3.14159265358979323846 
int del_x[4] = {-1, 1, 0, 0};
int del_y[4] = {0, 0, 1, -1};
int XX[8] = {-1, -1, -1, 0, 1, 1, 1, 0};
int YY[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
/////////////////////////// GLOBAL ///////////////////////////

template <int MOD_> class modnum {
	static constexpr int MOD = MOD_;
	static_assert(MOD_ > 0, "MOD must be positive");
 
private:
	using ll = long long;
 
	int v;
 
	static int minv(int a, int m) {
		a %= m;
		assert(a);
		return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
	}
 
public:
 
	modnum() : v(0) {}
	modnum(ll v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
	explicit operator int() const { return v; }
	friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
	friend std::istream& operator >> (std::istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }
 
	friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
	friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }
 
	modnum inv() const {
		modnum res;
		res.v = minv(v, MOD);
		return res;
	}
	friend modnum inv(const modnum& m) { return m.inv(); }
	modnum neg() const {
		modnum res;
		res.v = v ? MOD-v : 0;
		return res;
	}
	friend modnum neg(const modnum& m) { return m.neg(); }
 
	modnum operator- () const {
		return neg();
	}
	modnum operator+ () const {
		return modnum(*this);
	}
 
	modnum& operator ++ () {
		v ++;
		if (v == MOD) v = 0;
		return *this;
	}
	modnum& operator -- () {
		if (v == 0) v = MOD;
		v --;
		return *this;
	}
	modnum& operator += (const modnum& o) {
		v += o.v;
		if (v >= MOD) v -= MOD;
		return *this;
	}
	modnum& operator -= (const modnum& o) {
		v -= o.v;
		if (v < 0) v += MOD;
		return *this;
	}
	modnum& operator *= (const modnum& o) {
		v = int(ll(v) * ll(o.v) % MOD);
		return *this;
	}
	modnum& operator /= (const modnum& o) {
		return *this *= o.inv();
	}
 
	friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
	friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
	friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
	friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
	friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
	friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};
 
template <typename T> T power(T a, long long b) {
	assert(b >= 0);
	T r = 1; while (b) { if (b & 1) r *= a; b >>= 1; a = a*a; } return r;
}

const int mod = 1e9+7;
using Mint = modnum<mod>;
const int mxn = 5e5+1;

Mint f1[mxn],f2[mxn];
void init(){
	f1[0]=f2[0]=1;
	for(int i=1;i<mxn;i++){
		f1[i]=i*f1[i-1];
		f2[i]=inv(f1[i]);
	}
}
Mint choose(int n, int r){
	Mint ans = 1;
	ans = f1[n]*f2[r]*f2[n-r];
	return ans;
}
/////////////////////////// GLOBAL ///////////////////////////
void solve(){
	init();
	int n,m;
	cin >> n >> m;
	Mint ans = 0;
	int c = 1;
	for(int i=0;i<=n;i++){
		ans += c*choose(n,i)*choose(m-i,n-i)*f1[n-i];
		//deb(ans);
		c = -c;
	}
	cout << ans * choose(m,n)*f1[n] <<"\n";
	

}

int32_t main(){ 
	#ifndef ONLINE_JUDGE
		clock_t tStart = clock();
		freopen("TC", "r", stdin);
		//freopen("output.txt","w",stdout);
	#endif 
    ios_base:: sync_with_stdio(false); 
   	cin.tie(0); 
	int t=1;
	//cin >> t;
	for(int tt=1;tt<=t;tt++){
		//cout << "Case #"<<tt<<": ";
		solve();
	}
	#ifndef ONLINE_JUDGE
    	cerr << "\nRun Time -> "<<(double)(clock()-tStart)/CLOCKS_PER_SEC <<" sec\n";
    #endif
}

Measured memory_bytes: 7500