Third box is stage 2 and it has 2 rounds. In first round, there are 2 orange and green boxes that contains 4 elements. in this case, index 0 and 2 and 1 and 3 will be compared and sorted in ascending if orange box and in descending if green box. then in round 2, index 0 and 1 , 2 and 3 ... will be compared and sorted. Third box and Fourth box are same.