CF251D Two Sets

Little Petya likes numbers a lot. Recently his mother has presented him a collection of $ n $ non-negative integers. There's only one thing Petya likes more than numbers: playing with little Masha. He immediately decided to give a part of his new collection to her. To make the game even more interesting, Petya decided to give Masha such collection of numbers for which the following conditions fulfill: - Let's introduce $ x_{1} $ to denote the $ xor $ of all numbers Petya has got left; and let's introduce $ x_{2} $ to denote the $ xor $ of all numbers he gave to Masha. Value $ (x_{1}+x_{2}) $ must be as large as possible. - If there are multiple ways to divide the collection so that the previous condition fulfilled, then Petya minimizes the value $ x_{1} $ . The $ xor $ operation is a bitwise excluding "OR", that is denoted as "xor" in the Pascal language and "^" in C/C++/Java. Help Petya divide the collection as described above. If there are multiple suitable ways to divide it, find any of them. Please note that after Petya gives a part of his numbers to Masha, he may have no numbers left. The reverse situation is also possible, when Petya gives nothing to Masha. In both cases we must assume that the $ xor $ of an empty set of numbers equals 0.

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