program helenka;
uses Graph;

var
 grDriver: Integer;
 grMode: Integer;
 ErrCode: Integer;

 x1,x2,y1,y2: integer;

 function fx (x:real):integer;
  begin
    fx:=round (GetMaxX/2+x);
  end;

 function fy (y:real):integer;
 begin
    fy:=round (GetMaxY/2-y);
 end;



begin
 grDriver := Detect;
 InitGraph(grDriver, grMode,' ');
 ErrCode := GraphResult;
 if ErrCode = grOk then
 begin

   x1:=10; x2:=50; y1:=50; y2:=80;


   Rectangle(fx(x1),fy(y1),fx(x2),fy(y2));
   Readln;
   CloseGraph;
   writeln(x1,' ', fx(x1));
   writeln(x2,' ', fx(x2));
   writeln(y1, ' ', fy(y1));
   writeln(y2, ' ', fy(y2));
   writeln (GetMaxX, ' ', GetMaxY);
   Readln;
 end
 else
   Writeln('Chyba ovladace grafiky, doplnte egavga.bgi:', GraphErrorMsg(ErrCode));
end.