$list = []
$words = []
 
def index_of_list
  $words.map do |e1|
    ret = nil
    $list.map.with_index do |e2, i|
      if e2.index(e1)
        ret = i
        break
      end
    end
    ret
  end
end
 
def words_to_indexes
  w = index_of_list.flatten.compact.uniq
  if w == []
    $list << $words
  else
    $list[w.min] += $words
    $list.delete($list[w.max]) if w.min != w.max
    $list.map! do |e|
      e.uniq.sort
    end
  end
end
 
while w = gets
  w = w.chomp
  $words = w.split(' ')
  words_to_indexes
end
 
$list.map do |e|
  puts e.join(', ')
end
 

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goose pigeon
cat dog
eel goldfish
goose duck
horse dog
cod eel
dove pigeon
dog rhino
goldfish squid
goose lark