#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define szof(x) ((int)(x).size())
#define vi vector<int>
#define pii pair<int, int>
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
const int INF = INT_MAX;
const int LNF = INF*INF;
const int MOD = 1000000007;
const int mod = 998244353;
const double eps = 1e-12;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
const int MAX = 3010;
int n, m;
int dp[MAX][MAX];
int C2[MAX];
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
FOR(i, 0, MAX-1, 1){
C2[i] = i * (i-1) / 2;
}
FOR(i, 0, MAX-1, 1){
dp[i][0] = dp[0][i] = 1;
dp[i][1] = dp[1][i] = C2[i] + 4*i + 1;
}
FOR(ij, 4, 2*MAX-2, 1){
FOR(i, 2, ij-2, 1){
int j = ij - i;
if(i >= MAX or j >= MAX) continue;
dp[i][j] = C2[i] * dp[i-2][j-1] + i * (j-1) * dp[i-1][j-2] + 4 * i * dp[i-1][j-1] + dp[i][j-1];
//if(i <= 4 and j <= 4) cerr<<"dp["<<i<<"]["<<j<<"] = "<<dp[i][j]<<endl;
dp[i][j] %= MOD;
}
}
cin>>n>>m;
int res = dp[n][m] - 1;
if(res < 0) res += MOD;
cout<<res<<'\n';
/*
cerr<<"dp : "<<endl;
FOR(i, 0, 4, 1){
FOR(j, 0, 4, 1){
cerr<<dp[i][j]<<"\t";
}
cerr<<endl;
}
cerr<<endl;
*/
return 0;
}
