#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
int main() {
  long long x, res;
  cin >> x;
  res = x / 5;
  if (x % 5 != 0) res++;
  cout << res << endl;
  return 0;
}
