#include <bits/stdc++.h>
#define pb push_back
#define ppb pop_back
#define fi first
#define se second
#define mid ((x + y) / 2)
#define left (ind * 2)
#define right (ind * 2 + 1)
#define mp make_pair
#define timer ((double)clock() / CLOCKS_PER_SEC)
#define endl "\n"
#define spc " "
#define d1(x) cerr<<#x<<":"<<x<<endl
#define d2(x, y) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<endl
#define d3(x, y, z) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<" "<<#z<<":"<<z<<endl
#define fast_io() ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
using namespace std;
typedef long long int lli;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<double, double> dd;
const int N = (int)(3e3 + 5);
const int LOG = (int)(20);
const int mod = (int)(1e9 + 7);
lli n, m, dp[N][N];
lli f(lli x, lli y)
{
lli re = 0;
if(x < 0 || y < 0)
return 0;
if(x == 0 || y == 0)
return 1;
if(dp[x][y] != -1)
return dp[x][y];
re += f(x - 1, y);
re += f(x - 1, y - 2) * y * (y - 1) / 2;
re += f(x - 2, y - 1) * (x - 1) * y;
re += f(x - 1, y - 1) * 4 * y;
return dp[x][y] = re % mod;
}
int main()
{
fast_io();
// freopen("inp.in", "r", stdin);
cin >> n >> m;
memset(dp, -1, sizeof dp);
cout << f(n, m) - 1;
}
