class TrieNode:
    def __init__(self, data, is_word_end):
        self.data = data
        self.is_word_end = is_word_end
        self.children = {}
        
def add_word_to_trie(word, root):
    if len(word) <= 0:
        root.is_word_end = True
        return
    
    first_char = word[0]
    new_root = root.children.get(first_char, TrieNode(first_char, False))
    root.children[first_char] = new_root
            
    return add_word_to_trie(word[1:], new_root)
    
def has_prefix(word, root):
    if len(word) == 0:
        return False
    
    if root.is_word_end:
        return True
        
    next_root = root.children[word[0]]
    return has_prefix(word[1:], next_root)
    
def noPrefix(words):
    root = TrieNode('*', False)
    words_dict = {}
    for i in range(len(words)):
        add_word_to_trie(words[i], root)
        words_dict[words[i]] = words_dict.get(words[i], 0) + 1
    
    for i in range(len(words)):
        if has_prefix(words[i], root) or words_dict[words[i]] > 1:
            print('BAD SET')
            print(words[i])
            return

    print('GOOD SET')