#include <bits/stdc++.h>
using namespace std;
#include <math.h>
#include <iomanip>
#include <cstdint>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
#define rep(i,n) for (int i = 0; i < (n); ++i)
typedef long long ll;
typedef long double ld;
using P = pair<int,int>;
const int INF=1001001001;
const int mod =1e9+7;

void solve(){
  ll k;
  cin>>k;
  ll add=k*2+1;
  if(k==1){add=2;}
  if(k==2){add=k*2+1;}
  ll ans=(k*2+1)*k+max(k-1,1ll)*(k*2-1)+add;
  cout<<ans<<endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  return 0;
}