/*#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")*/
// only when really needed
/* GNU G++17 7.3.0: No long long for faster code
GNU G++17 9.2.0 (64 bit, msys 2): Long long only for faster code */
#include <bits/stdc++.h>
#define for1(i,a,b) for (int i = a; i <= b; i++)
#define for2(i,a,b) for (int i = a; i >= b; i--)
#define int long long
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pb push_back
/*
__builtin_popcountll(x) : Number of 1-bit
__builtin_ctzll(x) : Number of trailing 0
*/
#define PI 3.1415926535897932384626433832795
#define INF 1000000000000000000
#define MOD 1000000007
#define MOD2 1000000009
#define EPS 1e-6
using namespace std;
void add(int& a, int b) {
a += b;
if (a >= MOD) a -= MOD;
}
int mul(int a, int b) {
return a * b % MOD;
}
int n, m;
int dp[3005][3005];
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
// freopen("cf.inp", "r", stdin);
// freopen("cf.out", "w", stdout);
cin >> n >> m;
for1(i,0,n) dp[i][0] = 1;
for1(j,0,m) dp[0][j] = 1;
for1(i,1,n) {
for1(j,1,m) {
if (i > 1) add(dp[i][j], mul(dp[i - 2][j - 1], j * (i - 1)));
if (j > 1) add(dp[i][j], mul(dp[i - 1][j - 2], j * (j - 1) / 2));
add(dp[i][j], dp[i - 1][j]);
add(dp[i][j], mul(dp[i - 1][j - 1], 4 * j));
}
}
cout << (dp[n][m] - 1 + MOD) % MOD;
}
