#include<bits/stdc++.h>
#define ll long long
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
#define ull unsigned ll
using namespace std;
const int NMAX = 3001;
const ll mod = 1e9 + 7;
ll dp[NMAX][NMAX];
int main(){
int n, m; cin >> n >> m;
dp[0][0] = 1;
for(int i= 0; i <= n; i++) dp[i][0] = 1;
for(int j = 0; j <= m; j++) dp[0][j] = 1;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
dp[i][j] += dp[i - 1][j - 1] * 4 * j;
dp[i][j] += dp[i - 1][j];
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;
}
}
cout << (dp[n][m] - 1 + mod) % mod;
return 0;
}
