#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 3005;
const int MOD = 1e9 + 7;
long long dp[MAX_N][MAX_N];
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int H, W;
cin >> H >> W;
for(int i = 0; i <= W; i++) {
dp[0][i] = 1;
}
for(int i = 0; i <= H; i++) {
dp[i][0] = 1;
}
for(int i = 1; i <= H; i++) {
for(int j = 1; j <= W; j++) {
dp[i][j] += dp[i - 1][j];
dp[i][j] += dp[i - 1][j - 1] * j * 4;
if(i >= 2) {
dp[i][j] += dp[i - 2][j - 1] * j * (i - 1);
}
if(j >= 2) {
dp[i][j] += dp[i - 1][j - 2] * j * (j - 1) / 2;
}
dp[i][j] %= MOD;
}
}
dp[H][W]--;
dp[H][W] += MOD;
dp[H][W] %= MOD;
cout << dp[H][W];
return 0;
}
