#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e3+10;
const long long mod = 1e9+7;
typedef long long ll;
ll dp[maxn][maxn];
int main(void)
{
int n, m;
cin >> n >> m;
for (int i = 0; i < maxn; i++)
dp[i][0] = dp[0][i] = 1LL;
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= m; j++)
{
dp[i][j] = dp[i-1][j];
dp[i][j] = (dp[i][j] + (dp[i-1][j-1]*4LL*(ll)j))%mod;
if (j >= 2)
dp[i][j] = (dp[i][j] + (dp[i-1][j-2] * 1LL*(j*(j-1))/2))%mod;
if (i >= 2)
dp[i][j] = (dp[i][j] + (dp[i-2][j-1] * 1LL*(j*(i-1))))%mod;
}
}
cout << dp[n][m]-1LL << "\n";
}
