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

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