#include<iostream>
#include<iomanip>
#include<string>
#include<algorithm>
#include<vector>
#include<set>
#include<list>
#include<queue>
#include<math.h>
#include<bitset>
using ll = long long;
using namespace std;


int main(){
    ll n, n1, n2, ans;
    cin >> n;
    (!(n % 2)) ? (n1 = n/2) : (n1 = n/2 + 1);
    n2 = n - n1;
    cout << (n2 + 1)*(n1 + 1) -1 << endl;
}