/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.05.01 03:55:34
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    ll k;cin >> k;
    cout << (2*k+1)*(2*k+1)/2+1+(2*k-1)*(2*k-1)/2+1 << endl;
    return 0;
}