XOR is confusing, how do i make a 3 layered XOR gate?

ok so, in gui slot 0, 1 and 2, there should be only one item. if theres an item in 2 or 3 slots, then it shouldnt work, only one should be working, it doesnt matter which one. i tried using XOR gates, but it always made it to where, one works, 2 doesnt, but 3 works, it doesnt make sense to me at all, can someone help? this is frustrating, plus damaging the item doesnt work either. but im more worried about the XOR gates