#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 long int start = pow(k,2)- (k-1);
    long long int sum = start;
    for(int i =0; i<k-1 ;i++)
    {
        start += 2;
        sum += start;
    }
    
    return sum;
}

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