#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define len(a) (int)a.size()
#define all(a) (a.begin(),a.end())
#define fi first
#define sc second
#define ort(x,y) (x+y)/2
#define endl '\n'
#define FAST ios_base::sync_with_stdio(false);
#define d1(x) cerr<<#x<<":"<<x<<endl;
#define d2(x,y) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<endl;
#define d3(x,y,z) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<" "<<#z<<":"<<z<<endl;
#define N (int) (5e2+5)
#define M (int) ()
#define inf (int) (1e7)
#define p (1000000007)
#define heap priority_queue
#define mem(a,val) memset(a,val,sizeof(a))
#define y1 asdassa
typedef long long int lli;
typedef pair<int,int> pii;
typedef pair<pair<int,int>,int> piii;
lli k,t,ans;
int main()
{
	scanf("%lld",&k);
	t=k*k-k+1;
	while(k--)
	{
		ans+=t;
		t+=2;
	}
	printf("%lld\n",ans);
}