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// 2021-1-odd-od-deski-do-deski.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>

constexpr int MAXN = 3e3 + 7;
constexpr long long MD = 1e9 + 7;


// length, how many possible ends

// how many bad
long long dp[MAXN][MAXN];

// how many good
long long dp2[MAXN][MAXN];


int main()
{
	int n;
	long long m;
	std::cin >> n >> m;
	dp2[0][0] = 1;
	for (size_t l = 1; l <= n; l++)
	{
		for (long long i = 0; i <= l; i++)
		{
			dp[l][i] += dp[l - 1][i] * (m - i);
			dp[l][i] %= MD;
			dp2[l][i] += dp[l - 1][i] * i;
			dp2[l][i] %= MD;

			dp[l][i + 1] += dp2[l - 1][i] * (m - i);
			dp[l][i + 1] %= MD;
			dp2[l][i] += dp2[l - 1][i] * i;
			dp2[l][i] %= MD;
		}
		/*
		std::cout << l << ": \n";
		std::cout << "dp: ";
		for (size_t i = 0; i <= n; i++)
		{
			std::cout << dp[l][i] << ' ';
		}
		std::cout << "\ndp2: ";
		for (size_t i = 0; i <= n && i <= m; i++)
		{
			std::cout << dp2[l][i] << ' ';
		}
		std::cout << '\n';*/
	}
	long long answ = 0;
	for (size_t i = 0; i <= n; i++)
	{
		answ += dp2[n][i];
		answ %= MD;
	}
	std::cout << answ << '\n';
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file