#include <bits/stdc++.h>

using namespace std;

long calc(long n)
{
    return (n*(n+1))/2;
}

long sumOfGroup(long k) {
    long sum,total,i;
    sum=calc(k-1);
    sum*=2;
    sum+=1;
    for(i=0;i<k;i++)
    {
        total+=sum;
        sum+=2;
    }
    return total;
}

int main() {
    long k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}