#include <iostream>
#include <fstream>

using namespace std;


int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    int n , i = 1 ,s = 0;
    f >> n;
    while (i <= n){
        for(int j=1;j<=n;j++) s++;
        if(i>=2) {
            if(i%2==0) s=s-2;
            else s=s-1;
        }
        i++;
    }
    g << s;

    return 0;
}