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

long int sumOfGroup(int w) {
    // Return the sum of the elements of the k'th group.
    long int k=w;
    k=k-1;
    long int x=k*(k+1)/2;
    x=x+1;
    x=2*x-1;
    k=k+1;
    return (k*x+k*(k-1));
}

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