#include <fstream>


int main ()
 {

 long P,y,pres,presc=0,adaugat=0;

 std::ifstream f ("fact.in");
 f>>P;
 f.close();

 pres=P*4;
 presc+=pres/5;
 presc+=pres/25;
 presc+=pres/125;
 presc+=pres/625;
 presc+=pres/3125;
 presc+=pres/15625;
 presc+=pres/78125;
 presc+=pres/390625;
 presc+=pres/1953125;
 presc+=pres/9765625;
 presc+=pres/48828125;
 presc+=pres/244140625;
 presc+=pres/1220703125;

 while (pres%5!=0)
  {
   pres+=1;
   adaugat=1;
  }
  if (adaugat)
   presc++;
 while (presc<P)
  {
   y=pres;
   while ((y%5==0) && (y>0))
    {
     y=y/5;
     presc++;

    }
   pres+=5;

  }




  std::ofstream g ("fact.out");
 if (presc==P)
  g<<pres;
   else
  g<<-1;
 g.close();




 return 0;
 }