Suppose that is a list of numbers and is a permutation of these numbers, we say B is K-Manipulative if and only if:
is not less than , where represents the XOR operator.
You are given . Find the largest such that there exists a K-manipulative permutation .
Input:
The first line is an integer . The second line contains space separated integers - .
Output:
The largest possible , or if there is no solution.
Constraints:
Sample Input 0
3
13 3 10
Sample Output 0
2
Explanation 0
Here the list is . One possible permutation . Here
.
So there exists a permutation of such that is not less than . However there does not exist any permutation of such that is not less than . So the maximum possible value of is .
Sample Input 1
4
1 2 3 4
Sample Output 1
1
Explanation 1
Here the list is . One possible permutation . Here
.
So there exists a permutation of such that is not less than . However there does not exist any permutation of such that is not less than . So the maximum possible value of is .