class Graphe:
    def __init__(self):
        self.Liste = {}

    def addArete(self, u, v):
        if v not in self.Liste:
            self.Liste[v] = []
        if u not in self.Liste:
            self.Liste[u] = []
        self.Liste[u].append(v)
        self.Liste[v].append(u)

G = Graphe()
G.addArete('A', 'B')
G.addArete('A', 'D')
G.addArete('A', 'E')
G.addArete('C', 'B')
G.addArete('C', 'D')
G.addArete('D', 'E')
G.addArete('E', 'F')
G.addArete('E', 'G')
G.addArete('F', 'G')
G.addArete('G', 'H')
for key,value in G.Liste.items():
    print(key,":",value)