UVA 00913 - Joana and the Odd Numbers

#include <bits/stdc++.h>
#define EPS 1e-9
#define PI 3.14159265359
#define ii pair<int, int>
#define vi vector<int>

typedef long long ll;

using namespace std;

int main()
{
    int n;
    while(scanf("%d", &n) == 1){
        ll ans = ll(n/2) * (n / 2) * 2 + 1 + (n - 1) * 2;
        ans += 2 * ans - 6;
        cout<<ans<<endl;
    }

}