#include <bits/stdc++.h>
#define int long long
#define x first
#define y second
#define pb push_back
using namespace std;
using pii=pair <int,int>;
using tii=pair <pii,int>;
const int mod=1e9+7LL;
int dp[3010][3010];
void solve(){
int n,m;
cin>>n>>m;
dp[0][0]=1;
for (int i=0; i<n; i++){
for (int j=0; j<=m; j++){
dp[i+1][j]+=dp[i][j];
dp[i+1][j]%=mod;
if (j<m){
dp[i+1][j+1]+=4*dp[i][j]*(m-j);
dp[i+1][j+1]%=mod;
}
if (j<m-1){
dp[i+1][j+2]+=dp[i][j]*((m-j)*(m-j-1)/2%mod);
dp[i+1][j+2]%=mod;
}
if (i<n-1&&j<m){
dp[i+2][j+1]+=dp[i][j]*((m-j)*(n-i-1)%mod);
dp[i+2][j+1]%=mod;
}
}
}
int ans=0;
for (int i=0; i<=m; i++) ans=(ans+dp[n][i])%mod;
cout<<(ans+mod-1)%mod<<'\n';
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int t=1;
//cin>>t;
while (t--) solve();
}
