#include<bits/stdc++.h>
using namespace std;

signed main()
{
	ios::sync_with_stdio(0);
	
	long long n;
	cin >> n;
	
	if (n<=3)
	{
		cout << "0" << endl;
		return 0;
	}
	
	else
		cout << n*(n-1)/2*(n-2)/3*(n-3)/4 << endl; 
	
	return 0;
} 

交上去为啥会WA两个点?