Program So_Hanh_Phuc;
uses crt;
Var i,a,a1,b,b1,c,d: Longint;
BEGIN
Clrscr;
Write(' Cac so hanh phuc co 4 chu so la: ');
For i:=1000 to 9999 do begin a:= (i div 1000);
a1:= ( i mod 1000);
b:= a1 div 100;
b1:= a1 mod 100;
c:= b1 div 10;
d:= b1 mod 10;
If (a+b) = (c+d) then write(i,' ');
end;
Readln;
END.