Given an array of n integers, arr$[$n$],$ find the value of x that can be applied to the array to minimize the number of inversions. The array can be modified by applying the bitwise XOR to each element of the array with x$.$

An inversion in an array, arr, is a pair of indices $($i$,$ j$)$ where i $>$ j and arr$[$i$]<$ arr$[$j$].$

Example:

n $=3$

arr$=[8,5,2]$

For x $=12,$ the new array is $[4,9,14]$ after XOR. Number of inversions is $0.$ This is the minimum possible, so the answer is $0.$