#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define sz(x) (int)x.size()
#define endl '\n'
const int mod = 1e9 + 7;
const int inf = 2e9 + 5;
const ll linf = 9e18 + 5;
int n, m;
const int N = 3e3 + 5;
const int M = 3e3 + 5;
int dp[N][M];
int mull(int a, int b) {
return (1ll * a * b) % mod;
}
int c2(int n) {
return (1ll * n * (n - 1)) / 2;
}
void init() {
}
void input() {
cin >> n >> m;
}
void solve() {
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];
if (j >= 1) {
dp[i][j] += mull(mull(j, 4), dp[i - 1][j - 1]);
dp[i][j] %= mod;
}
if (i >= 2) {
dp[i][j] += mull(mull(j, i - 1), dp[i - 2][j - 1]);
dp[i][j] %= mod;
}
if (i >= 1 && j >= 2) {
dp[i][j] += mull(c2(j), dp[i - 1][j - 2]);
dp[i][j] %= mod;
}
}
}
cout << dp[n][m] - 1;
}
void output() {
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int number_of_testcases = 1;
//cin >> number_of_testcases;
while (number_of_testcases--) {
init();
input();
solve();
output();
}
return 0;
}
