#include <fstream>
using namespace std;

ifstream f("12perm.in");
ofstream g("12perm.out");

int sol, mod = (1 << 20), a[4], n;
int main()
{
    f >> n;

    a[1] = 2;
    a[2] = 6;
    a[3] = 12;
    for (int i = 3; i < n - 1; ++i)
    {
        int nr = a[2];
        a[2] = a[3];
        a[3] += a[1] + 2 * i;
        a[1] = nr;
    }

    g << a[3];
    g.close();
    return 0;
}