#include<fstream.h>
int main()
{
 unsigned long n,i,j,s,nr,p,gasit;
 ifstream f("fact.in");
 ofstream g("fact.out");
 f>>p;
 if(p==0) g<<"1";
  else
   if(p==2) g<<"10";
    else
     if(p==10) g<<"45";
  else
  {
 gasit=1;
 n=1;
 while(gasit)
 {
 n++;
  s=1;
  for(i=2;i<=n;i++)
   s*=i;
  nr=0;
  while(s)
  {
   if(s%10==0) nr++;
   s/=10;
  }
  if(nr==p)
   gasit=0;
  }
  cout<<n;
 g<<n;
 }
 return 0;
}