#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, p, ans;
  cin >> a;
  if (a % 2 != 0) {
    p = a / 2;
    ans = p + 1;
    cout << p << endl;
  } else {
    p = a / 2;
    cout << p << endl;
  }
}
