program vidu; var i: integer; procedure ctc; //var i:integer; begin i:=100; end; begin i:=1; ctc; writeln(i); readln end program baitap; uses crt; var a, b:integer; procedure tong(x,y:integer); var s:integer; begin s:=x+y; writeln('tong s=',s); end; begin clrscr; writeln('nhap so nguyen x,y '); readln(a,b); tong(a,b); readln end Tìm lỗi chương trình