#include <iostream.h>
#include <fstream.h>

#define MAXNR 10000000000LL
typedef unsigned long long ull;

ull get(ull c)
{
 ull nrr=0;   
 while(c%10==0)
 {
   nrr++;
   c/=10;            
 }   
}

int main()
{
 ifstream fin("fact.in");
 ofstream fout("fact.out");
 ull p,fn,i;
 fin >> p;
 bool ok;
 ull a=1;  
 ull b=5*p;  
 ull c=(a+b)/2;  
 c=c-c%5;  
 while(a<=c&&c<=b&&a<=b&&!ok)  
  {  
  fn=get(c); //get(c) returneaza zerourile pe care le are la sfarsit c!  
  if(fn==p)  
   {  
   ok=true;  
   i=c;  
   }  
  else if(fn<p)  
   a=c+1;  
  else  
   b=c-1;  
  c=(a+b)/2;  
  c=c-c%5;  
  }    
fout<<c;    
return 0;
}