You are given non-negative integers, . We define the score for some permutation () of length to be the maximum of for .
Find the permutation with the minimum possible score and print its score.
Note: is the exclusive-OR (XOR) operator.
Input Format
The first line contains single integer, , denoting the number of integers.
The second line contains space-separated integers, , describing the respective integers.
Constraints
Output Format
Print a single integer denoting the minimum possible score.
Sample Input 0
4
1 2 3 4
Sample Output 0
5
Sample Input 1
3
1 2 3
Sample Output 1
2
Explanation
Sample Case 0:
The permutation with the minimum score is :
Because the permutation's score is the maximum of these values, we print on a new line.
Sample Case 1:
The permutation with the minimum score is :
Because the permutation's score is the maximum of these values, we print on a new line.