#include<fstream.h>
int main()
{long int n,nr,a,OK=1,A=1;
ifstream fin("fact.in");
ofstream fout("fact.out");
fin>>nr;
  for(n=1;n<10000&&A==1;n++)
	{  a=n;
      while(a>0&&OK==1)
		{ OK=0;
		  if(a%10==0)
			{ nr=nr-1;
			  a=a/10;
			  OK=1;
            }
		}
	  while(a>0&&OK==1)
		{ OK=0;
		  if(a%5==0)
			{ nr=nr-1;
			  a=a/5;
			  OK=1;
            }
		}
	if(nr==0) A=0;
	}
	
fout<<n;
return 0;
}