Let G be a directed acyclic graph with labels on each of the vertices. Consider a path v_1, ..., v_n in G, and now consider the concatenation C of the labels on v_1, ..., v_n in the order of the path. A palindrome is a string that is equal to its reversal. C may or may not be a palindrome. Design and analyze an efficient algorithm that finds the length of the longest palindrome of any path in G, or correctly reports that no palindrome on any path exists (i.e., returns 0)