* Line 1: Two space-separated integers, N and M.
* Lines 2..N: Line i+1 contains a single integer p(i), denoting the parent of node i in the tree (0 <= p(i) < i).
* Lines N+1..N+M: Line N+i describes the ith sequence known not to occur in the code. The line will contain v(i) and s(i) separated by a space, where v(i) is the starting node of the sequence, and s(i) is a 5-digit string known not to occur starting at v(i) and proceeding upward in the tree. It is guaranteed that the root is at least 4 steps upward from v(i).