#include <iostream>


using namespace std;


int main()
{
    int a;
    int b;
    cin>>a>>b;
    if(a==b)
        cout<<"0"<<endl;
    else{
        int x=b-a;
        int petki;
        int kusur;
        int dvojki;
        int edinici;
        int vkupno;
    petki=x/5;
    kusur=x%5;
    dvojki=kusur/2;
    edinici=kusur%2;
    vkupno=petki+dvojki+edinici;
    cout<<vkupno<<endl;
    }


   return 0;
}