#include<iostream>
using namespace std;
int main(){
   int n,pente,tria,enos;
    cin>>n;
    pente=n/5;
    n=n%5;
    tria=n/3;
    enos=n%3;
    cout<<pente+tria+enos;

return 0;
}

/*29/5=5
29%5=4
4/3=1
4%3=1*/