public static void noPrefix(List<String> words) {
        //Sorting would make this faster, but their examples show we would reach the wrong result if sorted
        
        Trie trie = new Trie();
        for (String word : words) {
            //System.out.println("Add " + word + " to trie of size " + trie.size());
            if (trie.add(word)) {
                //overlap detected
                System.out.println("BAD SET");
                System.out.println(word);
                return;
            }
        }
        
         System.out.println("GOOD SET");
        
    }
    
    static class Trie extends HashMap<Character, TrieNode> {
               
        /* returns true if an overlap is detected */       
        public boolean add(String word) {
            char c = word.charAt(0);
            TrieNode n = get(c);
            if (n == null) {
                //System.out.println("=> Adding " + c + (word.length() == 1? " (Word End)":" (Node)"));
                n = new TrieNode(word);
                put(c,n);
                return false; //its a new node it cant be an overlap
            } else {
                //System.out.println("=> Updating " + c);
                //We already have the first char as n, so just try the rest
                if (word.length() > 1) { 
                    return n.add(word.substring(1));
                } else {
                    n.isWordEnd = true; //its a word end now since we reached finalletter of a word
                }
            }
            return n.isWordEnd;
        }
        
    }
    
    static class TrieNode {
        
        boolean isWordEnd = false;
        Trie branch = null;
        char c;
        
        public TrieNode(char c, boolean isWordEnd) {
            this.c = c;
            this.isWordEnd = isWordEnd;
        }
        
        public TrieNode(String c) {
            this(c.charAt(0), c.length() == 1);
            if (c.length() > 1) {
                add(c.substring(1));
            }
        }
        
        /* method assumes, this is letters after c, that c is already trimmed */
        /* returns true if an overlap is detected */   
        public boolean add(String word) {
            if (branch == null) {
                branch = new Trie();
            } 
            //System.out.println("=> Add " + word.charAt(0) + " after " + c);
            return isWordEnd || branch.add(word);
        }
               
    }