program Bai_tap;

uses Crt ;

var a,b,c,d,DTB:real;

begin

writeln('Nhap diem dia:');

readln(a);

writeln('Nhap diem ly:');

readln(b);

writeln('Nhap diem hoa:');

readln(c);

writeln('Nhap diem tin:');

readln(c);

DTB:=(a+b+c+d)/4;

writeln('Diem trung binh =',DTB:6:2);

readln;

end.

uses crt;
var dtb:real;
    a,b,c,d:longint;
begin
clrscr;
repeat
  write('Nhap diem mon toan (1->10): ');readln(a);
  write('Nhap diem mon ly (1->10): ');readln(b);
  write('Nhap diem mon hoa (1->10): ');readln(c);
  write('Nhap diem mon tin (1->10): ');readln(d);
until (0<a) and (0<b) and (0<c) and (0<d)
  and (11>a) and (11>b) and (11>c) and (11>d);
dtb:=(a+b+c+d)/4;
writeln('Diem trung binh cac mon: ',dtb:0:2);
readln;
end.