B"// We decided to drop the legend about the power sockets but feel free to come up with your own :^) Define a chain: You are given n chains of lengths l_1, l_2, ... , l_n . You plan to build a tree using some of them. The distance between two vertices of the tree is the number of edges on the shortest path between them. If there is at least k white vertices in the resulting tree, then the value of the tree is the distance between the root and the k -th closest white vertex. What's the minimum value of the tree you can obtain? If there is no way to build a tree with at least k white vertices, then print -1. The first line contains two integers n and k ( 1 <= n <= 2 cdot 10^5 , 2 <= k <= 10^9 ) -- the number of chains and the minimum number of white vertices a tree should have to have a value. The second line contains n integers l_1, l_2, ... , l_n ( 3 <= l_i <= 2 cdot 10^5 ) -- the lengths of the chains. Print a single integer. If there is no way to build a tree with at least k white vertices, then print -1. Otherwise, print the minimum value the tree can have. You are allowed to not use all the chains, so it's optimal to only use chain of length 4 in the second example. "...