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

long int sumOfGroup(long int k) {
    // Return the sum of the elements of the k'th group.
    long int i=0,j,sum=0;
    j=k*(k-1)+1;
    while(i<k)
    {
        sum=sum+j;
        j+=2;
        i++;
    }
    if(k==0)
        return k;
    else
        return sum;
    
}

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