#include <iostream>
#include <stdio.h>
#include <cmath>
#include <map>
#include <set>
#include <cstring>
#include <stdlib.h>
#include <algorithm>
#include <vector>
#include <iomanip>
#define ull unsigned long long 
#define ul unsigned long
#define ll long long
#define ld long double
#define gcode __gcd
#define bitcoin __builtin_popcount
#define check(n, pos) (n & (1<<pos))
#define set(n, pos) (n | (1<<pos)) 
using namespace std;

ull highest(ull a,ull b){
	return (a>b)?a:b;
}
ull smallest(ull a,ull b){
	return (a<b)?a:b;
}
vector<int>ini;
vector<int>pb;
vector<int>name;
vector<int>life;
vector<char>who;
vector<char>love;
set<int>kshe;
set<int>namenai;
map<char,int>mp;
vector<pair<int,int> >mk; 
long long lalaland[100009],lala[100009];

int main(){
	int n;
	cin>>n;
	long am=(n*2)+1;
	//cout<<am<<endl;
	long long sum=0;
	for(int i=0;i<n;i++){
		sum+=(am+2*i);
		//cout<<sum<<" ";
	}
	cout<<sum<<endl;
   // cerr<<"time elapsed: "<<clock()*1000.0/CLOCKS_PER_SEC<<"ms"<<"\n";
	return 0;
}