630H - Benches - CodeForces Solution

#include <cstdio>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <math.h>
#include <iostream>
#include <time.h>
#include <stdlib.h>
#include <iomanip>
#include <fstream>
#include <locale>
using namespace std;
#define ull unsigned long long
#define ll long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define EPS 1e-6
const double PI = acos(-1);
const ll mod = 1e9 + 7;
const ll INF = 1e18;
ll _;

void solve() {
	ull n;
	cin >> n;
	ull ans = n;
	for (ull k = 1; k < 5; k++) {
		ans *= (n - k);
	}
	cout << ans / 120 * ans << endl;
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int t = 1;
	while (t--) {
		solve();
	}
	return 0;
}
/* Fri Feb 24 2023 13:47:55 GMT+0300 (Moscow Standard Time) */