#include <fstream.h>
#include <iostream.h>
int main()
{
   ifstream fin("fact.in");
   ofstream fout("fact.out");
   long n=0,ct=0,p,cap=5;
//   cin>>p;
   fin>>p;
   while (ct<p)
   {
    n=n+1;
    ct=ct+1;
    if (n==cap)
    {
     ct=ct+1;
     cap=5*cap;
    }
   }
   n=n*5;
   if (p==0) n=1;
   if (ct!=p) n=-1;
//   cout<<n;
   fout<<n;
   return 0;
}