program password;
uses crt;
var tk, mk: string;
begin
 repeat
 clrscr;
  textcolor (white);
  writeln ('Dang nhap de thoat khoi chuong trinh');
   write ('nhap ten tai khoan: ');   readln (tk);
   write ('nhap mat khau: ');     readln (mk);
   if (tk='taikhoan_123') and (mk='123456789') then exit;
   if (tk<>'taikhoan_123') or (mk<>'123456789') then

   begin

   clrscr;
   writeln ('ten tai khoan hoac mat khau bi sai. vui long dang nhap lai');
   readln;

   end;
  until (tk='taikhoan_123') and (mk='123456789');
 readln;
end.

tên tài khoản: taikhoan_123

mật khẩu:  123456789

uses crt;
var tk, mk: string;
begin
repeat
clrscr;
textcolor (red);
writeln ('Dang nhap de thoat khoi chuong trinh');
write ('nhap ten tai khoan: '); readln (tk);
write ('nhap mat khau: ');  readln (mk);
if (tk='baonamok114') and (mk='baonam123') then
exit;
if (tk<>'nam123') or (mk<>'123456789') then
textcolor (lightred);
writeln ('ten tai khoan hoac mat khau bi sai. vui long dang nhap lai');
readln;
until (tk='vnqt343') and (mk='123456789');
readln;
end.