# Input: lines like "<code>-<code>"
# Output: largest connected set, sorted alphabetically, joined by commas

connections = {}

file = open("23_input.txt", "r")
for line in file:
  line = line.replace("\n", "")
  parts = line.split("-")
  if not (parts[0] in connections):
    connections[parts[0]] = []
  connections[parts[0]].append(parts[1])
  if not (parts[1] in connections):
    connections[parts[1]] = []
  connections[parts[1]].append(parts[0])

max_connections = 0
for code in connections:
  if max_connections < len(connections[code]):
    max_connections = len(connections[code])

def fully_connected(set):
  for i in range(len(set) - 1):
    for i2 in range(i + 1, len(set)):
      if not (set[i] in connections[set[i2]]):
        return False
  return True

def subset_with_enough_connections(set, target_connections):
  if len(set) == target_connections:
    if fully_connected(set):
      return set
    else:
      return None
  for code in set:
    set2 = set.copy()
    set2.remove(code)
    subset = subset_with_enough_connections(set2, target_connections)
    if subset != None:
      return subset
  return None

result = None
target_connections = max_connections + 1
while result == None:
  for code in connections:
    if len(connections[code]) < target_connections:
      continue
    set = connections[code].copy()
    set.append(code)
    result = subset_with_enough_connections(set, target_connections)
    if result != None:
      break
  target_connections -= 1

result.sort()
result_string = ""
for code in result:
  result_string += "," + code
print (result_string[1:])