#include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define ll long long
using namespace std;
const ll mod=1e9+7;
ll dp[3005][3005],n,m;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0),cout.tie(0);
cin>>n>>m;
for (int i=0; i<=max(n,m); i++){
dp[i][0]=1; dp[0][i]=1;
}
for (int i=1; i<=n; i++)
for (int j=1; j<=m; j++){
dp[i][j]=dp[i-1][j]+dp[i-1][j-1]*j*4%mod;
if (i>1) dp[i][j]+=dp[i-2][j-1]*j*(i-1)%mod;
if (j>1) dp[i][j]+=dp[i-1][j-2]*j*(j-1)/2%mod;
dp[i][j]%=mod;
}
cout<<dp[n][m]-1<<endl;
}
