#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
int n,m;
ll dp[3001][3001];
ll solve(int x,int y){
if(x<=0||y<=0)return 1;
if(dp[x][y]!=-1)return dp[x][y];
dp[x][y]=0;
dp[x][y]+=solve(x-1,y);
dp[x][y]+=solve(x-1,y-2)*(ll)((y*(y-1))/2);
dp[x][y]+=solve(x-1,y-1)*(ll)(y*4);
dp[x][y]+=solve(x-2,y-1)*(ll)(y*(x-1));
dp[x][y]%=M;
return dp[x][y];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>m;
REP(i,0,3001)REP(j,0,3001)dp[i][j]=-1;
cout<<solve(n,m)-1;
}
