#include <stdio.h>

 int main(){

         int k,sum;

         while(scanf("%d",&k)!=EOF){

             if(k%==){

                 sum=(+k)*(k/);

             }

             else{

                 sum=(+k)*(k/)+k/+;

             }

             printf("%d\n\n",sum);

         }

     return ;

 }