Gửi cô Hiền

program ma_hien;
uses crt;
var ctl:string;
procedure kt;
    begin
    while (ctl<>'roi') or (ctl<>'chua') do
        begin
            write('Cau tra loi khong hop le! Nhap lai cau tra loi: ');
                readln(ctl);
        if (ctl='roi') or (ctl='chua') then break;
        end;
    exit;
    end;
{------------------------}
procedure chua;
    begin
    while ctl='chua' do
        begin
        writeln('Ve nha di!');
        write('Ve den nha chua? ');
        readln(ctl);
        if ctl='roi' then break;
        if ctl<>'chua' then
        begin
            write('Cau tra loi khong hop le! Nhap lai cau tra loi: ');
            continue;
                        end;
        end;
    end;
{------------------------}
procedure roi;
    begin
    writeln('Tot! O yen day!');
        readln;
    halt;
    end;
{---------------------}
begin
    clrscr;
    writeln('Chi tra loi "roi" hoac "chua"!');
    write('Da o nha chua? ');
    readln(ctl);
    if (ctl<>'roi') and (ctl<>'chua') then kt; (Kiem tra cau tra loi co hop le}
    if ctl = 'roi' then roi;
{Chuong trinh se ket thuc neu tra loi roi va se chay tiep phan code duoi neu cau tra loi la chua}
    writeln('Ve nha di!');
    write('Ve den nha chua? ');
    readln(ctl);

    if (ctl<>'roi') and (ctl<>'chua') then kt; (Kiem tra cau tra loi co hop le)
        if ctl = 'roi' then roi else chua;
    if ctl='roi' then roi else chua;
    readln;
end.