680. Chess Knight Problem
You enjoy playing Chess and are tasked with finding the shortest distance a knight can travel from a given source to a given destination on a chessboard.
The first line contains the coordinates of the source point, x1 and y1, separated by a space. The second line contains the coordinates of the destination point, x2 and y2, also separated by a space.
Print the minimum number of steps taken by the knight to reach the destination from the given source.
0 7 7 0
0 <= x1, y1, x2, y2 <= 7