program fact;
var f,g:text;
    p,i,j,k,nr:longint;
    ok:boolean;
begin
  assign(f,'fact.in');
  reset(f);
  readln(f,p);
  close(f);

  assign(g,'fact.out');
  rewrite(g);
  if p=0 then
   begin
    write(g,1);
    close(g);
    halt;
   end else
  begin

  ok:=false; i:=0;
  repeat
   i:=i+5;
   nr:=0;
   for j:=1 to i do
    begin
     k:=j;
     while (k mod 5=0) and (k<>1) do
      begin
       inc(nr);
       k:=k div 5;
      end;
    end;
   if nr>=p then
    ok:=true;
  until ok=true;

  write(g,i);
  close(g);
  end;
end.