class Node():
    def __init__(self, char):
        self.char = char
        self.children = dict()
        self.end = False

def noPrefix(words):
    trie = Node("")
    for i in range(len(words)):
        word = words[i]
        head = trie
        for i in range(len(word)):
            char = word[i]
            new_head = head.children.get(char)
            if new_head:
                if i == len(word) -1 or new_head.end:
                    print("BAD SET")
                    print(word)
                    exit()
                head = new_head
            else:
                head.children[char] = Node(char)
                head = head.children[char]
                if i == len(word) -1:
                    head.end = True
    print("GOOD SET")