#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;
int Q[3001][3001];
int dp(int x, int y){
if(x < 0 || y < 0) return 0;
if(x == 0 || y == 0) return Q[x][y] = 1;
if(Q[x][y] != -1) return Q[x][y];
int ret = 0;
ret += dp(x - 1, y - 2) * ((y - 1) * y / 2) % modulo;
ret += dp(x - 2, y - 1) * y * (x - 1) % modulo;
ret %= modulo;
ret += dp(x - 1, y - 1) * 4ll * y % modulo;
ret += dp(x - 1, y) % modulo;
return Q[x][y] = ret % modulo;
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, m;
cin >> n >> m;
for(int i = 0; i <= n; i++){
for(int j = 0; j <= m; j++){
Q[i][j] = -1;
}
}
cout << (dp(n, m) - 1 + modulo) % modulo << endl;
}
