#!/usr/bin/python
# -*- coding: utf-8 -*-

M={"A":{"B","D"},"B":{"A","F","G","H"},"C":{"E","F"},"D":{"A","E"},
    "E":{"C","D","F","H"},"F":{"B","C","E","H"},"G":{"B","H"},"H":{"B","E","F","G"}}
afaire={"G"}
fait=set()
while afaire:
  temp=set()
  for s in afaire:
    temp|=M[s]
  temp-=fait
  temp-=afaire
  fait|=afaire
  afaire=set(temp)
  print(temp)