Fuck those people so fucking hard. If you are group 3 or 4 there is a high chance you will not get to bring you carry on because fucking pricks have brought not one, but sometimes TWO full sized suitcases and stashed them overhead. So they make you check your carry on. Oh ho ho that pisses me off to no end, however you can get around it if you carry a soft (non rolly or hard boxed bag) if it is a soft bag they will let you take it with you and remove someones hard bag as they can't force you to check breakables etc in a soft bag/duffle.