Game of Thrones#11542
Be careful here is spoiler
George Martin writes last volume of A Song of Ice and Fire. In this volume Daenerys Targaryen will take Iron throne. But firstly she needs to find the maximum protection value of Seven kingdoms for the first attack. Tyrion Lannister as military adviser needs to help her. You can assume that Seven kingdoms is a rectangle and each cell has its own protection value. Protection value of an area is the xor of all cells in it. Tyrion needs to choose some rectangle with maximum protection value. The sides of rectangle must be parallel to the sides of 7 kingdoms. Help him to find such area.
The first line contains two integers — n, m~(1 \le n, m \le 300), the height and the width of a Kingdom.
Each of the next lines contains integers a_{i,j}~(0 \le a_{i,j} < 2^{16}), protection value of the cell .
Print one integer — the answer to the problem.
Example 1