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 Ai_{1}, Ai_{2}, ..., Ai_{k} (1 <= i_{1} < i_{2} < ... < i_{k} <= N) such, that Ai_{1} XOR Ai_{2} XOR ... XOR Ai_{k} 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 Ai_{1} XOR Ai_{2} XOR ... XOR Ai_{k}.