// High above the clouds there is a rainbow...
#include<bits/stdc++.h>
#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int maxn=3010,mod=1e9+7;
const ll inf=1e18;
int dp[maxn][maxn];
int C(int n){
if(n<2) return 0;
return (1ll*n*(n-1) /2) %mod;
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);
int n,m;cin>>n>>m;
dp[0][0]=1;
for(int j=1;j<=m;j++){
dp[0][j]=1;
dp[1][j]=(C(j) + 4*j + 1) %mod;
}
for(int i=1;i<=n;i++){
dp[i][0]=1;
dp[i][1]=(C(i) + 4*i + 1) %mod;
}
for(int i=2;i<=n;i++){
for(int j=2;j<=m;j++){
dp[i][j]=(1ll*C(j)*dp[i-1][j-2] + 1ll*(i-1)*(j)*dp[i-2][j-1] + 4ll*j*dp[i-1][j-1] + 1ll*dp[i-1][j] )%mod;
}
}
int ans=dp[n][m]-1;
if(ans<0) ans+=mod;
return cout<<ans<<endl,0;
}
// Deathly mistakes:
// * Read the problem curfully.
// * Check maxn.
// * Overflows.
