B'You are given a rooted tree consisting of n vertices numbered from 1 to n . The root is vertex 1 . There is also a string s denoting the color of each vertex: if s_i = texttt{B} , then vertex i is black, and if s_i = texttt{W} , then vertex i is white. A subtree of the tree is called balanced if the number of white vertices equals the number of black vertices. Count the number of balanced subtrees. A tree is a connected undirected graph without cycles. A rooted tree is a tree with a selected vertex, which is called the root. In this problem, all trees have root 1 . The tree is specified by an array of parents a_2, ... , a_n containing n-1 numbers: a_i is the parent of the vertex with the number i for all i = 2, ... , n . The parent of a vertex u is a vertex that is the next vertex on a simple path from u to the root. The subtree of a vertex u is the set of all vertices that pass through u on a simple path to the root. For example, in the picture below, 7 is in the subtree of 3 because the simple path 7 to 5 to 3 to 1 passes through 3 . Note that a vertex is included in its subtree, and the subtree of the root is the entire tree. The first line of input contains an integer t ( 1 <= t <= 10^4 ) -- the number of test cases. The first line of each test case contains an integer n ( 2 <= n <= 4000 ) -- the number of vertices in the tree. The second line of each test case contains n-1 integers a_2, ... , a_n ( 1 <= a_i < i ) -- the parents of the vertices 2, ... , n . The third line of each test case contains a string s of length n consisting of the characters texttt{B} and texttt{W} -- the coloring of the tree. It is guaranteed that the sum of the values n over all test cases does not exceed 2 cdot 10^5 . For each test case, output a s'...