program factorial;
var p,c,f,g:longint;
    n:int64;
    i,o:text;
begin
  assign(i,'fact.in');
  reset(i);
  read(i,p);
  assign(o,'fact.out');
  rewrite(o);
  if p=0 then
    write(o,'1')
  else
  begin
  c:=0;
  f:=0;
  n:=0;
  repeat
    n:=n+5;
    c:=c+1;
    g:=c;
    while g mod 5=0 do
      begin
      f:=f+1;
      g:=g div 5
      end
  until c+f>=p;

  if c+f=p then
    write(o,n)
  else
    write(o,'-1')
  end;
  close(o)
end.