#include<bits/stdc++.h>
#define int long long
using namespace std;
const int mod=1e9+7;
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n,m;
cin>>n>>m;
int dp[n+1][m+1];
memset(dp,0,sizeof(dp));
for(int j=0;j<=m;j++) dp[0][j]=1;
for(int i=1;i<=n;i++){
for(int j=0;j<=m;j++){
dp[i][j]=dp[i-1][j-1]*4*j%mod;
dp[i][j]=(dp[i][j]+dp[i-1][j])%mod;
if(j>1) dp[i][j]=(dp[i][j]+dp[i-1][j-2]*(j*(j-1)/2%mod)%mod)%mod;
if(i>1) dp[i][j]=(dp[i][j]+dp[i-2][j-1]*j%mod*(i-1)%mod)%mod;
}
}
cout<<(dp[n][m]-1+mod)%mod;
}
