class Vertex {
  String label;
  
  Vertex(String label)
  {
    this.label = label;
  }
}

class Edge {
  Vertex a, b;
  
  Edge(Vertex a, Vertex b)
  {
    this.a = a; this.b = b;
  }
}

class Graph {
  Vertex[] vertices;
  Edge[] edges;
 
  // Display the labels of the vertices and of the vertices for the edges 
  void print()
  {
    println("Vertices"); println("--------");
    for (int i=0; i<vertices.length; i++)
      println(vertices[i].label);

    println(); println("Edges"); println("-----");
    for (int i=0; i<edges.length; i++)
      println(edges[i].a.label+","+edges[i].b.label);
  }
}