from typing import List

class TrieNode: def init(self): self.children = {} self.is_end_of_word = False

class Trie: def init(self): self.root = TrieNode()

def insert_and_check(self, word: str) -> bool:
    node = self.root
    for char in word:
        if char not in node.children:
            node.children[char] = TrieNode()
        node = node.children[char]
        if node.is_end_of_word:  # Current node is end of another word
            return False
    node.is_end_of_word = True
    if node.children:  # Current word is a prefix of another word
        return False
    return True

def check_prefix(self, word: str) -> bool:
    node = self.root
    for char in word:
        if char not in node.children:
            return False
        node = node.children[char]
    return True

def noPrefix(words: List[str]) -> None: trie = Trie()

for word in words:
    if trie.check_prefix(word):
        print("BAD SET\n" + word)
        return
    if not trie.insert_and_check(word):
        print("BAD SET\n" + word)
        return

print("GOOD SET")