Faktorial Mod 998244353
#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
void solve() {
int n; cin >> n;
if (n & 1) {
cout << "0\n";
return;
}
long long ans = 1;
for (int i = 1; i <= n ; ++i) {
ans *= 1LL * i * i % MOD;
ans %= MOD;
}
cout << ans << '\n';
}
Adorable Alpaca