Write a program in Python please.

Write an algorithm that finds the length of the longest path starting from vertex 0 in a DAG. The input consists of a sequence of one or more DAGs. Each DAG D is represented by an adjacency list. The first line is an integer n that indicates the order of D. This is followed by n white space separated lists of adjacencies for vertices labeled 0 to n - 1. The input is terminated by a line consisting of a single zero. This line should not be processed. Each input DAG may contain up to 5000 vertices and 10000 arcs. An example input that contains two DAGs is shown next. The output is a sequence of lines, one for each input DAG. Each line contains a single integer indicating the length of the longest path starting from vertex 0. Write an algorithm that finds the length of the longest path starting from vertex 0 in a DAG. The input consists of a sequence of one or more DAGs. Each DAG D is represented by an adjacency list. The first line is an integer n that indicates the order of D. This is followed by n white space separated lists of adjacencies for vertices labeled 0 to n - 1. The input is terminated by a line consisting of a single zero. This line should not be processed. Each input DAG may contain up to 5000 vertices and 10000 arcs. An example input that contains two DAGs is shown next. The output is a sequence of lines, one for each input DAG. Each line contains a single integer indicating the length of the longest path starting from vertex 0