Chef and Submatrix

Chef has a square matrix A. He would like to choose a consecutive sub-matrix of A such that value of bitwise XOR of all elements in it is maximal. Each sub-matrix can be defined by four numbers (x1,y1,x2,y2), with the meaning that the submatrix contains an element A[i][j] iff x1 ≤ i ≤ x2 and y1 ≤ j ≤ y2. You can read more about bitwise XOR operation here. Input The first line of the input cont