#include<iostream>
#include<fstream>
using namespace std;

int main()
{
  int nr2=0,nr5=0;
  long p,t=1,y;
  ifstream f("fact.in");
  ofstream g("fact.out");
  f>>p;
  if(p==5)g<<-1;
  else 
  if(!p)g<<1;
  else {
  while(nr5<=p-1)
  {
   y=t;
   while(y%5==0 && nr5<=p-1)
   {
    nr5++;
    y/=5;
   } 
  t++;
  }
  }
  g<<t-1;
  return 0;
 
}