Maximum XOR of a Pair

Difficulty: 1800 3500 ms 128 MB

bitwise

Choose two elements (possibly equal indices forbidden, N ≥ 2) maximizing a_i ⊕ a_j. Print the maximum XOR.

Input: the first line has N; the second line has N non-negative integers.

Output: the maximum pairwise XOR.

Constraints:

• 2 ≤ N ≤ 10⁵
• 0 ≤ a_i < 2³⁰

Sample Tests

3
2 4 5

7

2
8 8

0

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