Tham Khảo:
uses crt;
var ngay:integer;
lp:string;
begin
clrscr;
repeat
write('nhap so ngay thue phong khach san:'); readln(ngay);
if ngay<=0 then writeln('nhap lai');
until ngay>0;
repeat
write('nhap loai phong:'); readln(lp);
if (lp<>'A') and (lp<>'B') and (lp<>'C') then writeln('nhap lai');
until (lp='A') or (lp='B') or (lp='C');
case lp of
'A': write(300000*ngay);
'B': write(250000*ngay);
'C': write(200000*ngay);
end;
readln;
end.