#include <bits/stdc++.h>
#include <ostream>
#define pb push_back
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define ll long long
#define left h*2,l,(l + r)/2
#define right h*2+1,(l + r)/2 + 1,r
#define int ll
using namespace std;
const int N = 3000 + 5,mod = 1e9 + 7;
int dp[N][N];
signed main() {
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n,m;
cin>>n>>m;
for (int i = 0; i <= n; i++)
for (int j = 0; j <= m; j++)
if (i*j==0) dp[i][j] = 1;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= m; j++){
dp[i][j] = dp[i - 1][j];
if (j >= 2) dp[i][j] += dp[i - 1][j - 2] * ((j* (j - 1))/2) % mod;
dp[i][j] %= mod;
if (i >= 2) dp[i][j] += dp[i - 2][j - 1] * j * (i - 1) % mod;
dp[i][j] %= mod;
dp[i][j] += dp[i - 1][j - 1] * 4 * j % mod;
dp[i][j] %= mod;;
}
}
cout<<((dp[n][m] - 1)%mod + mod)%mod;
}
