#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

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; }

using namespace std;
typedef long long ll;
using P = pair<ll, ll>;

int dx[] = {1, 1, -1, -1, 0};
int dy[] = {1, -1, 1, -1, 1};

ll solve(ll k){
    map<P, int> dist;
    dist[P(0, 0)] = 0;
    queue<P> que;
    que.push(P(0, 0));
    while(!que.empty()){
        auto [x, y] = que.front(); que.pop();
        int d = dist[P(x, y)];
        if(d == k) continue;
        for(int k = 0; k < 5; k++){
            P p(x+dx[k], y+dy[k]);
            if(dist.count(p) == 0){
                que.push(p);
                dist[p] = d+1;
            }
        }
    }
    return dist.size();
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    ll k; cin >> k;
    if(k == 1){
        cout << 6 << endl;
        return 0;
    }
    cout << 6+4*(k-1)*(k+1) << endl;
}