#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a, b, c, d, e;
  cin >> n;
  a = n / 5;
  b = (n - a * 5) / 4;
  c = (n - a * 5 - b * 4) / 3;
  d = (n - a * 5 - b * 4 - c * 3) / 2;
  e = (n - a * 5 - b * 4 - c * 3 - d * 2);
  cout << a + b + c + d + e << endl;
  return 0;
}
