#include <fstream.h>

int main()
{
 int nr,aux=0,n,auxi;   
 ifstream fin("fact.in");
 fin>>nr;
 fin.close();
 
 ofstream fout("fact.out");
 if(nr==0)
  fout<<'1';
 else
 {
  aux=0;
  n=0;
  auxi=0;   
  while(n<nr)
  {
   aux=aux+5; 
   for(auxi=aux;(auxi%5==0);auxi=auxi/5)                          
    n++;            
  }
  fout<<aux;
 }    
 
 fout.close();
 return 0;
}