#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; }