#include<bits/stdc++.h>
using std::cin;
using std::cout;
using std::endl;
using ll = long long;

int main(){
    ll K; cin >> K;
    ll ans = (2*K+1)*(2*K+1)/2 + (2*K-1)*(2*K-1)/2 + 2;
    cout << ans << endl;
}