#include <bits/stdc++.h>

using namespace std;

#define int long long
#define f first
#define s second

typedef pair<int, int> ii;

const int N = 5005;
const int MOD = 1e9 + 7;

int n, m;
int dp[N + 5][N + 5];

void solve() {
    cin >> n >> m;
    for (int i = 0; i <= n; ++i)
        for (int j = 0; j <= m; ++j) {
            if (!i || !j) {
                dp[i][j] = 1LL;
                continue;
            }
            dp[i][j] += dp[i][j - 1]; // put nothing
            dp[i][j] = (dp[i - 1][j - 1] * i * 4 + dp[i][j]) %
                       MOD; //  1 tent only on j-th col
            if (i >= 2)
                dp[i][j] = (dp[i - 2][j - 1] * i * (i - 1) / 2 + dp[i][j]) %
                           MOD; // 2 tents on j-th col
            if (j >= 2)
                dp[i][j] =
                    (dp[i - 1][j - 2] * (j - 1) * i + dp[i][j]) %
                    MOD; // 2 tents on 1 row, 1 tent must be put on j column,
                         // thats why * (j - 1) instead of j * (j - 1) / 2
            // generally say, must put at least 1 tent at new j-th column
        }
    cout << (dp[n][m] - 1) % MOD;
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    freopen("flagger.inp", "r", stdin);
    freopen("flagger.out", "w", stdout);
    int test;
    if (0)
        cin >> test;
    else
        test = 1;
    while (test--) {
        solve();
    }
}