#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;
using maxt = atcoder::modint1000000007;

int main() {
  int N;
  cin >> N;
  N /= 2;
  if(N % 2 == 1) {
    cout << N + 1 << endl;
  }
  else {
    cout << N << endl;
  }
}