#include <stdio.h>
int n;
void solve ()
{
    if (n==1)
        printf ("1");
    else if (n==2)
        printf ("2");
    else if (n==3)
        printf ("6");
    else if (n==4)
        printf ("12");
}
int main ()
{
	freopen ("12perm.in","r",stdin);
	freopen ("12perm.out","w",stdout);
	int i,a=1,b=2,c=6,d=12,e;
	scanf ("%d",&n);
    if (n<5)
        solve ();
    else
    {
        for (i=5; i<=n; ++i)
        {
            e=d+b+2*(i-2);
            a=b;
            b=c;
            c=d;
            d=e;
        }
        printf ("%d",e); 
    }
	return 0;
}