#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
#define maxsize 100000

long int sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
     long int index=0,sum=0,j,count;
     long int arr[maxsize],i;

    for(i=1,j=0;i<=100000;i++)
    {
        if(i%2!=0)
        {
            arr[j]=i;
            j++;
        }
    }

    //To find the starting index for k
    for(i=(k-1);i>=0;)
    {
         index=index+i;
         i=i-1;
    }
    //To find the sum of the numbers in that group
    for(i=index,count=0;count<k;count++,i++)
        sum=sum+arr[i];

    return(sum);
}

int main() {
    int k;
    scanf("%i", &k);
    long int answer = sumOfGroup(k);
    printf("%ld\n", answer);
    return 0;
}