//# include "stdafx.h"

# define _CRT_SECURE_NO_DEPRECATE
# include <fstream>
# include <iostream>
# include <stdlib.h>
# include <queue>
# include <string>
# include <cstdio>
# include <stdio.h>
# include <math.h>
# include <algorithm>
# include <vector>
# include <unordered_map>
# include <set>
# include <map>
# include <iomanip>
# include <math.h>
# include <stack>
# include <functional>
# define inf 9223372036854775807
# define mp make_pair
# define pb push_back
# define FOR(k,a,z) for (int k=a;k<z;k++)
# define pi 3.14159265359
# define maxlong long 2147483647
# define ll long long

#include <cstdio>
#include <cstring>
#define LSOne(S) (S & (-S))
#define MAXLOG 50
#include <sstream>
#include <utility>

#define P 100000
#define INF 1000000000

using namespace std;




int main() {
   // freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
    ll n;
    cin>>n;

    ll l = ((n-1)*(n))/2;
    l=l*2-1;

    l+=2;
    ll z = l;

    FOR(k,0,n-1) {
        z+=2;
        l+=z;
    }

    cout<<l;




    return 0;
}