#include "bits/stdc++.h"

using namespace std;

void solve(void)
{
	long n;
	cin >> n;
	if (n == 1)
	{
		cout << 0 << endl;
		return;
	}
	long ans = (n & 1 ? (n*n*n+3*n*n+5*n-3)/6 : (n*n*n+3*n*n+5*n-6)/6);
	cout << ans << endl;
}

int main()
{
	solve();
	//cout << "yui(*-v・)yui" << endl;
	return 0;
}