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#pragma GCC optimize ("O3")
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef double K;
constexpr int INF = 0x3f3f3f3f;

#define FOR(i, b, e) for(int i = (b); i < (e); i++)
#define TRAV(x, a) for(auto &x: (a))
#define SZ(x) ((int)(x).size())
#define PB push_back
#define X first
#define Y second

constexpr int mod = 1e9 + 7;
constexpr int N = 3010;

int kon[N], zdr[N], nos[N], zak[N];

void solve() {
	int n, m;
	cin >> n >> m;
	kon[2] = 1;
	FOR(i, 1, n + 1) {
		for(int j = n; j >= 0; j--) {
			nos[j + 2] = 1ll * zak[j + 2] * (m - j - 1) % mod;
			zak[j + 2] = (1ll * zdr[j + 2] + nos[j + 1] + zak[j + 2]) * j % mod;
			zdr[j + 2] = (1ll * kon[j + 2] + zdr[j + 2] + nos[j + 1]) * (m - j) % mod;
			kon[j + 2] = (1ll * zdr[j + 1] + nos[j] + zak[j + 1]) % mod;
		}
	}
	int sum = 0;
	FOR(i, 0, n + 3) sum = (sum + kon[i]) % mod;
	cout << sum << '\n';
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	// int tt; cin >> tt;
	// FOR(te, 0, tt) {
	// 	// cout << "Case #" << te + 1 << ": ";
	// 	solve();
	// }
	solve();
	return 0;
}