uses crt;
var
  s: ^shortstring;
begin
  clrscr;
  new(s);
  write('Nhap vao cau van cua ban: '); readln(s^);
  s^[length(s^)+1] := #5; s^[0] := #5;
  while s^[1] <> #5 do
  begin
    s := @s^[1];
  end;
  //s đang ở kí tự cuối cùng
  s := s-1;
  while s^[255] <> #5 do
  begin
    s := s+1;
    write(s^[0]);
    s := s-1;
    s := @s^[255];
    s := s-1;
  end;
  s := s+1;
  write(s^[0]);
end.