#include <cstdio>

using namespace std;

int n;
int nr[5];

void citire()
{
    scanf("%d", &n);
}

int solve()
{
    nr[0] = 1;
    nr[1] = 2;
    nr[2] = 6;
    nr[3] = 12;

    if(n <= 4)
    {
        return nr[n - 1];
    }

    nr[0] = 2;
    nr[1] = 6;
    nr[2] = 12;

    for(int i = 4; i < n; i++)
    {
        nr[3] = nr[2] + nr[0] + 2 * (i - 1);
        nr[0] = nr[1];
        nr[1] = nr[2];
        nr[2] = nr[3];
    }

    return nr[3];
}

int main()
{
    freopen("12perm.in", "r", stdin);
    freopen("12perm.out", "w", stdout);

    citire();
    printf("%d", solve());

    return 0;
}