#include <bits/stdc++.h>
//#include <atcoder/dsu>
//using namespace atcoder;
//#pragma GCC optimize("Ofast")
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()

using ll = long long;
using vec = vector<ll>;
using mat = vector<vec>;

ll N,M,H,W,Q,K,A,B;
string S;
using P = pair<ll, ll>;
using tp = tuple<ll, ll, ll>;
const ll INF = (1LL<<61);

template<class T> bool chmin(T &a, const T b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T b){
    if(a < b) {a = b; return true;}
    else return false;
}
template<class T> void my_printv(std::vector<T> v,bool endline = true){
    if(!v.empty()){
        for(std::size_t i{}; i<v.size()-1; ++i) std::cout<<v[i]<<" ";
        std::cout<<v.back();
    }
    if(endline) std::cout<<std::endl;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cin>>K;
    auto calc = [](ll k){
        return (k * 2 + 1) * (k * 2 + 1) / 2 + 1;
    };
    cout<<calc(K - 1) + calc(K)<<endl;
}