# adjacency list

class Vertex:
    def __init__(self,n):
        self.name=n
        self.neighbors=list()

    def add_neighbor(self,v):
        if v not in self.neighbors: 
            self.neighbors.append(v)
            self.neighbors.sort()
            
class Graph:
    vertices = {}

    def add_vertex(self,vertex):
        if isinstance(vertex, Vertex) and vertex.name not in self.vertices:
            self.vertices[vertex.name]=vertex
            return True
        else:
            return False
    
    def add_edge(self, u ,v):
        if u in self.vertices and v in self.vertices:
            for key , value in self.vertices.items():
                if key == u:
                    value.add_neighbor(v)
                if key == v:
                    value.add_neighbor(u)
            return True
        else:
            return False
    def print_graph(self):
        for key in sorted(list(self.vertices.keys())):
            print(key + str(self.vertices[key].neighbors))

g = Graph()
a = Vertex('A')
g.add_vertex(a)
g.add_vertex(Vertex('B'))
for i in range(ord('A'),ord('K')):
    g.add_vertex(Vertex(chr(i)))

edges = ['AB' , 'AE' , 'BF' , 'CG' ,'DE','DH','EH','FG','FI','FJ','GJ','HI']
for edge in edges:
    g.add_edge(edge[:1],edge[1:])
g.print_graph()