uses crt;
var tk, mk : string;
begin
clrscr;
write('nhap tai khoan : '); readln(tk);
write('nahp mat khau : '); readln(mk);
while (tk <> 'vnqt343') or (mk <> '123456789') do
begin
write('nhap lai tai khoan : '); readln(tk);
write('nahp lai mat khau : '); readln(mk);
end;
readln
end.