#include <iostream>
#include <stdio.h>
#include <vector>
#include <map>
#include <stack>
#include <cstring>
#include <set>
#include <utility>
#include <iostream>
#include <iomanip>
#include <list>
#include <queue>
#include <algorithm>
#include <cmath>
//#include <boost/multiprecision/cpp_int.hpp>
#include <unordered_set>
#include <bitset>
#include <cassert>
#include <numeric>
#include <complex>
#define FOR(i,a,b) for (ll i=(a);i<(ll)(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define SUM(v) accumulate(ALL(v),0ll)
using ll = long long;
const ll INF=10e10;
const ll eps=1;
const double pi=3.14159265359;
const ll mod=10000000000+7;
using namespace std;
//Union Find テンプレ
struct UnionFind {
  vector<int> par , siz;
  UnionFind(int n) : par(n,-1) , siz(n,1) { }
  int root(int x) {
    if(par[x] == -1) return x;
    else return par[x] = root(par[x]);
  }
  bool issame(int x, int y) {
    return root(x) == root(y);
  }
  bool unite(int x, int y) {
    x = root(x) ; y = root(y);
    if(x == y) return false;
    if(siz[x] < siz[y]) swap(x,y);
    par[y] = x;
    siz[x] += siz[y];
    return true;
  }
  int size(int x) {
    return siz[root(x)];
  }
};
ll k;
vector<ll> dp(k+5);
string s;
int main()
{
  cin>>k;
  if(k==1)
  {
    cout<<1<<endl;
    return 0;
  }
  ll ans=4*k*k+2;
  cout<<ans<<endl;
  return 0;
}