#include <bits/stdc++.h> using namespace std; #define int long long signed main() { int n; cin >> n; int ji = 1; int sum = 0; for(int i = 2;i <= n;i++) { if(n - sum - i < i + 1) { ji *= (n - sum); break; } else { ji *= i; sum += i; } } cout << ji << endl; }