#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long
#define ff first
#define ss second
#define N 3005
#define MOD 1000000007
#define INF 0x3f3f3f3f
ll dp[N][N];
ll c[N][N];
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m;
cin>>n>>m;
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] + (j >= 2 ? j * (j - 1) / 2 * dp[i - 1][j - 2] : 0) + 4 * j * dp[i - 1][j - 1] + (i >= 2 ? dp[i - 2][j - 1] * j * (i - 1) : 0)) % MOD;
cout<<(dp[n][m] + MOD - 1) % MOD;
}
