Random

ll bigmod(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b & 1)
            res = res * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return res;
}

ll ret(int n, int m) {
    ll ans = 1;
    for (int i = 2; i <= n; i++) {
        ans = ans * i % MOD;
    }
    ll res = 0;
    for (ll k = 1; k <= m; k++) {
        res = (res + bigmod(k * (k + 1), MOD - 2)) % MOD;/// works because co-prime
    }
    return (ans * res) % MOD;
}