#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000

set<pair<int,int>> S;

void dfs(int y,int x,int remain){
	S.insert(make_pair(y,x));
	if(remain==0)return;
	
	dfs(y+1,x,remain-1);
	dfs(y+1,x+1,remain-1);
	dfs(y+1,x-1,remain-1);
	dfs(y-1,x+1,remain-1);
	dfs(y-1,x-1,remain-1);
}

int main(){
	
	long long K;
	cin>>K;
	
	cout<<K*K*4+2<<endl;
	
    return 0;
}