#include <bits/stdc++.h>
#define ll long long 
using namespace std;

ll sumOfGroup(ll k) {
    if(k==1)
        return 1;
    ll summ = 0;
    ll val =(k)*(k-1)+1;
    for(int i=0;i<k;i++){
        summ+=(val);
        val+=2;
    }
    return summ;
    // Return the sum of the elements of the k'th group.
}

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