#include <algorithm>
#include <iostream>
#include <cassert>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <cstdio>
#include <string>
#include <vector>
#include <cmath>
#include <ctime>
#include <queue>
#include <stack>
#include <map>
#include <set>

using namespace std;

#define pii pair<int,int>
#define ll long long
#define N (int)(2e5+10)
#define mod 1000000007
#define mp make_pair
#define pb push_back
#define nd second
#define st first
#define inf mod
#define endl '\n'
#define sag (sol+1)
#define sol (root*2)
#define ort (bas+son)/2
#define bit(x,y) ((x>>y)&1)
int i,j,k,n,m,x,y,z,arr[N];
int ata[N],mx[N],L[N],R[N],wh[N],ans,H[N];

ll f(ll x){
	x = (x+1)/2;
	return x*x;
}

int main(){
	ll n;
	cin >> n;


	cout << f(n*(n+1)-1) - f(n*(n-1)-1)  << endl;
}