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

long int sum(long int n)
{
    return (n*n + n)/2;
}

long int sumOfGroup(long int k) {

    long int start = 2*sum(k-1)+1;
    return (start*k + 2*sum(k-1));
    
}

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