Question :

Given 2 arrays 'A' and 'B' both of size 'N'. Make 'N' pairs ( A[ i ], B[ j ] ) such that :

1. First element of pair should be from array 'A' and second element from array 'B'. ( we cannot make pair ( A[1], A[3] ) )
2. An element cannot occur in more than one pair. { i.e for every 2 pairs ( A[i], B[j] ) , ( A[k], B[l] ) (i != k and j != l) }
3. Let the value of a pair be the XOR of first and second element of the pair, value of all the pairs formed must be equal.

Constraints : 0 <= A[i], B[i] <= 10^9 __________ ( 1 <= i <= N )

( Consider N even as the problem can be solved for odd N in O(N) easily )

How to solve it in less than O(N^2) Time Complexity ?

If not possible return -1