#include<stdio.h>
#include<limits.h>

FILE *in=fopen("fr.in","r");
FILE *out=fopen("fr.out","w");

int n,p,q;

void read()
{
 fscanf(in,"%d",&n);
}

int cmmdc(int a,int b)
{
 int r=a%b;
 while(r)
  {
   a=b; b=r; r=a%b;
  }
 return b;
}

void calcul()
{
 int nr=0;
 for(p=1;p<=n;p++)
  {
   if(p==1) nr+=n;
   if(p%2&&p!=1) nr+=n-1;
   if(p%2==0&&n%2) nr+=n-2;
   if(p%2==0&&n%2==0) nr+=n-2;
  }
 fprintf(out,"%d",nr);
}

int main()
{
 read();
 calcul();
 return 0;
}