#include <fstream>

using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");

long long n,p,nr,putere;
int main()
{
    f>>p;

    while (p>0)
     {
         putere=0;
         nr=1;
         while (putere<=p+1)
         {
             putere=putere*5+1;
             nr*=5;
         }
         n+=nr/5;
         p-=(putere-1)/5;

     }
     if (p==0)
      g<<n;
     else
      g<<"-1";
    f.close();
    g.close();
}