CF1438D Powerful Ksenia

Ksenia has an array $ a $ consisting of $ n $ positive integers $ a_1, a_2, \ldots, a_n $ . In one operation she can do the following: - choose three distinct indices $ i $ , $ j $ , $ k $ , and then - change all of $ a_i, a_j, a_k $ to $ a_i \oplus a_j \oplus a_k $ simultaneously, where $ \oplus $ denotes the [bitwise XOR operation](https://en.wikipedia.org/wiki/Bitwise_operation#XOR). She wants to make all $ a_i $ equal in at most $ n $ operations, or to determine that it is impossible to do so. She wouldn't ask for your help, but please, help her!

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In the first example, the array becomes $ [4 \oplus 1 \oplus 7, 2, 4 \oplus 1 \oplus 7, 4 \oplus 1 \oplus 7, 2] = [2, 2, 2, 2, 2] $ .