# 14109-HUTI ## Hint For two numbers they are the same, the xor operation result will be 0: ![same](https://hackmd.io/_uploads/Bk3MhEv4a.png) If a number X "XOR" 0, the xor operation result will still be X: ![X](https://hackmd.io/_uploads/S1Mq3NPE6.png) So since the order of xor operation will not change the result, you can reduce the paired numbers by just "XOR" them.