One way to define a transportation system is with a set of sequences of vertices, each sequence defining a path connecting the vertices. For example, the sequence 0-9-3-2 defines the edges 0-9, 9-3, and 3-2. Write a program that builds a graph from an input file consisting of one sequence per line, using symbolic names. Develop input suitable to allow you to use your program to build a graph corresponding to the Paris metro system.