#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, rez = 0;
  scanf("%d", &x);
  while (x >= 5) x -= 5, rez++;
  while (x >= 4) x -= 4, rez++;
  while (x >= 3) x -= 3, rez++;
  while (x >= 2) x -= 2, rez++;
  while (x >= 1) x--, rez++;
  printf("%d", rez);
  return 0;
}
