#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
#include <iostream>
using namespace std;


long int sumOfGroup(int k) {
    long x = k-1;
    long ans1 = x*k;


    long sum = 0, cnt=1;

    for(long i = ans1+1; cnt<=k; i+=2){
        cnt++;
        //cout << sum << " ";
        sum += i;
    }

    return sum;
}

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