#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
//---------------------------------------------------------------------------------------------------






typedef long long ll;
ll K;
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> K;

    ll top = K * (K - 1) / 2;
    ll a1 = top * 2 + 1;
    ll n = K;
    ll an = a1 + 2 * (K - 1);

    ll ans = n * (a1 + an) / 2;
    cout << ans << endl;
}