#include <bits/stdc++.h>
using namespace std;
int x, ans, i;
int s[] = {5, 4, 3, 2, 1};
int main() {
  cin >> x;
  while (x != 0) {
    if (x >= s[i]) {
      x -= s[i];
      ans++;
    } else {
      i++;
    }
  }
  cout << ans;
  return 0;
}
