P3571 [POI 2014] SUP-Supercomputer

Byteasar has designed a supercomputer of novel architecture. ```plain It may comprise of many (identical) processing units. ``` Each processing unit can execute a single instruction per time unit. The programs for this computer are not sequential but rather have a tree structure. Each instruction may have zero, one, or multiple subsequent instructions, for which it is the parent instruction. The instructions of the program can be executed in parallel on all available processing units. Moreover, they can be executed in many orders: the only restriction is that an instruction cannot be executed unless its parent instruction has been executed before. For example, as many subsequent instructions of an instruction that has been executed already can be executed in parallel as there are processing units. Byteasar has a certain program to run. Since he likes utilizing his resources optimally, he is wondering how the number of processing units would affect the running time. He asks you to determine, for a given program and number of processing units, the minimum execution time of the program on a supercomputer with this many processing units. Equivalent formulation: You are given a rooted tree with $n$ nodes, with root $1$. There are $q$ queries; in each query, a number $k$ is given. In one step, you may visit up to $k$ unvisited vertices whose parents have already been visited. Find the minimum number of steps needed to visit the whole tree for each given $k$.

In the first line of standard input, there are two integers, $n$ and $q$ ($1\le n, q\le 1\,000\,000$), separated by a single space, that specify the number of instructions in Byteasar's program and the number of running time queries (for different numbers of processing units). In the second line of input, there is a sequence of $q$ integers, $k_1, k_2, \ldots, k_q$ ($1\le k_i\le 1\,000\,000$), separated by single spaces: $k_i$ is the number of processing units in Byteasar's $i$-th query. In the third and last input line, there is a sequence of $n-1$ integers, $a_2, a_3, \ldots, a_n$ ($1\le a_i

Your program should print one line consisting of $q$ integers, separated by single spaces: the $i$-th of these numbers should specify the minimum execution time of the program on a supercomputer with $k_i$ processing units.

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