B"You are given a rooted tree, consisting of n vertices. The vertices are numbered from 1 to n , the root is the vertex 1 . You can perform the following operation at most k times: The height of a tree is the maximum depth of its vertices, and the depth of a vertex is the number of edges on the path from the root to it. For example, the depth of vertex 1 is 0 , since it's the root, and the depth of all its children is 1 . What's the smallest height of the tree that can be achieved? The first line contains a single integer t ( 1 <= t <= 10^4 ) -- the number of testcases. The first line of each testcase contains two integers n and k ( 2 <= n <= 2 cdot 10^5 ; 0 <= k <= n - 1 ) -- the number of vertices in the tree and the maximum number of operations you can perform. The second line contains n-1 integers p_2, p_3, ... , p_n ( 1 <= p_i < i ) -- the parent of the i -th vertex. Vertex 1 is the root. The sum of n over all testcases doesn't exceed 2 cdot 10^5 . For each testcase, print a single integer -- the smallest height of the tree that can achieved by performing at most k operations. "...