public static void noPrefix(List<string> words)
    {
        var hashSetData = new Dictionary<string,List<int>>();
        var num = words.Count;
        var prefixes = new List<string>();
        for(int i = 0 ; i< num ; i++) {
            var word = words[i];
            if(hashSetData.ContainsKey(word)) { hashSetData[word].Add(i);}
            else {
                var data = new List<int>();
                data.Add(i);
                hashSetData.Add(word , data );
            }
        }
        var nextIndexCheckData = num + 1;
        for(int i = 0 ; i < num ; i++) {
            var word = words[i];
            if(i == nextIndexCheckData) {
                Console.WriteLine("BAD SET\n" + word);
                return;
            }
            var length = word.Length;
            for(int j = length ; j >= 1 ; j--) {
                var subString = word.Substring(0 , j);
                if(hashSetData.ContainsKey(subString)) {
                    var data = hashSetData[subString];
                    foreach(var idx in data) {
                        if(idx < i) {
                            Console.WriteLine("BAD SET\n" + word);
                            return;
                        } else if (idx > i && idx < nextIndexCheckData) {
                            nextIndexCheckData = idx;
                        }
                    }
                }
            }
        }
        
        Console.WriteLine("GOOD SET");
    }