procedure servad; 
var i: integer;
begin
 clrscr;
 textbackground(green);
 gotoxy(1, 1);
 for i:=1 to 80 do write(' ');
 for i:=1 to 24 do
 begin
  gotoxy( 1, i); write(' ');
  gotoxy(80, i); write(' ');
 end;
 gotoxy(1, 24);
 for i:=1 to 80 do write(' ');
 textbackground(black);
end;