You are an amazon delivery and you have some boxes that you have to deliver, but there are some conditions - You can take 2 boxes of same weight in one round you can take 3 boxes of same weight in one round You have to find the minimum number of rounds to deliver the boxes or -1 if it is not possible to deliver them. Example cases - Input: boxes - [2, 2, 3, 3, 2, 4, 4, 4, 4, 4] Output: 4 Explanation: 3 boxes of weight 2 in 1st round, 2 boxes of weight 3 in 2nd round, 3 boxes of wt 4 in 3rd and 2 boxes of wt 4 in 4th round. Input: boxes - [2, 3, 3] Output: -1 Explanation: There is only one box with weight 2 and we can only take either 2 or 3 boxes in one round not lesser.