class TrieNode {
        TrieNode[] children = new TrieNode[26];
        boolean isEndOfWord = false;
    }

     class Result {
        public static void noPrefix(List<String> words) {
            TrieNode root = new TrieNode();
            for (String word : words) {
                if (!insert(root, word)) {
                    System.out.println("BAD SET");
                    System.out.println(word);
                    return;
                }
            }
            System.out.println("GOOD SET");
        }

        private static boolean insert(TrieNode root, String word) {
            TrieNode current = root;
            for (int i = 0; i < word.length(); i++) {
                int index = word.charAt(i) - 'a';
                if (current.children[index] == null) {
                    current.children[index] = new TrieNode();
                }
                current = current.children[index];
                if (current.isEndOfWord) {
                    return false;
                }
            }
            current.isEndOfWord = true;
            for (TrieNode child : current.children) {
                if (child != null) {
                    return false;
                }
            }
            return true;
        }
    }