Problem Statement

You are given a sequence of $N non-negative integers A=(A_1,A_2,\dots,A_N).$ Consider performing the following operation N-1 times on this sequence to obtain a sequence of length 1:

• Let n be the length of A. First, rearrange the elements in A in any order you like.
  Then, replace A with a sequence of $n-1 non-negative integers (A_1 \oplus A_2, A_2 \oplus A_3, \dots, A_{n-1} \oplus A_n)$.

Here, $\oplus$ represents the bitwise $\mathrm{XOR}$ operation.
Let X be the value of the term contained in the sequence of length 1 obtained after N-1 operations. Find the maximum possible value of X.

    What is the bitwise $\mathrm{XOR}$ operation?


    The bitwise $\mathrm{XOR}$ of two non-negative integers A and B, denoted as $A \oplus B$, is defined as follows:

• In the binary representation of $A \oplus B$, the digit at the $2^k (k \geq 0)$ position is 1 if the digit at the 2^k position is 1 in A or B but not both, and 0 otherwise.

  For example$, 3 \oplus 5 = 6 ($in binary: $011 \oplus 101 = 110)$.  
  In general, the bitwise $\mathrm{XOR}$ of $k non-negative integers p_1, p_2, p_3, \dots, p_k$ is defined as $(\dots ((p_1 \oplus p_2) \oplus p_3) \oplus \dots \oplus p_k)$, and it can be proved that this does not depend on the order of $p_1, p_2, p_3, \dots, p_k$.
  

Input

The input is given from Standard Input in the following format:
N
$A_1 A_2 \dots A_N$

Output

Print the answer.

Constraints

• $2 \leq N \leq 100$
• $0 \leq A_i < 2^{60}$
• All input values are integers.

Sample Input 1

4
1 2 3 4

Sample Output 1

7

The sequence A can be transformed into A=(7) by the following three operations:

• In the first operation, rearrange A=(1,2,3,4) to (3,1,4,2). A is replaced with $(3 \oplus 1, 1 \oplus 4, 4 \oplus 2) = (2,5,6)$.
• In the second operation, rearrange A=(2,5,6) to (2,6,5). A is replaced with $(2 \oplus 6, 6 \oplus 5) = (4,3)$.
• In the third operation, rearrange A=(4,3) to (4,3). A is replaced with $(4 \oplus 3) = (7)$.

Sample Input 2

13
451745518671773958 43800508384422957 153019271028231120 577708532586013562 133532134450358663 619750463276496276 615201966367277237 943395749975730789 813856754125382728 705285621476908966 912241698686715427 951219919930656543 124032597374298654

Sample Output 2

1152905479775702586

见题面 Input 部分

见题面 Output 部分