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

ll int sumOfGroup(ll int k) 
{
    ll int sum=0,p=k;
    for(ll i=(k*(k-1))+1;p--;i+=2)
        sum+=i;
    return (sum);
}

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