#include<iostream>
#include<set>
#include<vector>
#include<math.h>
#include<stdio.h>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
//#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<long long,long long> pll;
typedef vector<int> vi;
typedef vector<long long> vll;
#define pb push_back
template<typename T>void read(T &x)
    {
        register T c = getchar(); x = 0; int t = 0;
        if (c == '-') t = 1, c = getchar();
        for (; (c < 48 || c > 57); c = getchar());
        for (; c > 47 && c < 58; c = getchar()) {
            x = (x << 1) + (x << 3) + c - 48;
        }
        if (t) x = -x;
    }
int main()
{
//ios_base::sync_with_stdio(false); cin.tie(NULL);
ll k,sum=0;
cin>>k;
ll i=(k*(k-1))+1;
ll cnt=0;
while(cnt<k)
{
    sum+=i;
    i+=2;
    cnt++;
}
cout<<sum;
}