#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
using namespace std ;
const ll N = 3000, mod = 1e9 + 7 ;
ll dp[N + 1][N + 1] ;
signed main()
{
ios_base::sync_with_stdio( 0 ) ;
cin.tie( 0 ) ;
cout.tie( 0 ) ;
ll n, m ;
cin >> n >> m ;
for(ll j = 0 ; j <= N ; j++)
dp[0][j] = dp[j][0] = 1 ;
for(ll i = 1 ; i <= n ; i++)
for(ll j = 1 ; j <= m ; j++)
{
dp[i][j] += dp[i - 1][j] ;
dp[i][j] += dp[i - 1][j - 1] * 4ll * j ;
if(j >= 2)
dp[i][j] += dp[i - 1][j - 2] * (j * (j - 1) / 2ll) ;
if(i >= 2)
dp[i][j] += dp[i - 2][j - 1] * (j * (i - 1)) ;
dp[i][j] %= mod ;
}
cout << (dp[n][m] - 1 + mod) % mod ;
return 0 ;
}
