275. To xor or not to xor

time limit per test: 0.25 sec.
memory limit per test: 65536 KB
input: standard
output: standard



The sequence of non-negative integers A1, A2, ..., AN is given. You are to find some subsequence Ai1, Ai2, ..., Aik (1 <= i1 < i2 < ... < ik <= N) such, that Ai1 XOR Ai2 XOR ... XOR Aik has a maximum value.

Input
The first line of the input file contains the integer number N (1 <= N <= 100). The second line contains the sequence A1, A2, ..., AN (0 <= Ai <= 10^18).

Output
Write to the output file a single integer number -- the maximum possible value of Ai1 XOR Ai2 XOR ... XOR Aik.

Sample test(s)

Input
3
11 9 5

Output
14
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Author:Michael R. Mirzayanov
Resource:ACM ICPC 2004-2005, NEERC, Southern Subregional Contest
Date:Saratov, October 7, 2004











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