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, ..., Ai_k (1 <= i₁ < i₂ < ... < i_k <= N) such, that Ai₁ XOR Ai₂ XOR ... XOR Ai_k has a maximum value.

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).

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

Input

3
11 9 5