#include <iostream>
#include <fstream>
using namespace std;
int main ()
{
 unsigned int nrzero = 0 , p ;
 long int i , j = 10 ;
 fstream f("fact.in",ios::in );
 f >> p ;
 f.close();    
 while ( nrzero < p )
 {
  while( i % 5 == 0 )
  {
   nrzero++;
   i /= 5 ;
  }
  i = j ;
  j += 5 ;
 }
 fstream g ("fact.out",ios::out );
 if( nrzero == p )g<< i - 5 ;
 else g<<-1 ;
 return 0 ; 
}