using System;
using System.Collections.Generic;

namespace No342
{
    class Program
    {
        enum LoopMode
        {
            search,
            count_w,
            count_text
        }

        static void Main(string[] args)
        {
            LoopMode mode = LoopMode.search; 
            int count_w = 0;
            string count_text = "";
            int max_text = 0;
            List<string> result_text = new List<string>();

            string text = "ｗ" + Console.ReadLine();

            for (int i = text.Length - 1; i >= 0; i--)
            {
                switch(mode)
                {
                    case LoopMode.search:
                        if (text[i] == 'ｗ')
                        {
                            mode = LoopMode.count_w;
                            count_w = 1;
                        }
                        break;

                    case LoopMode.count_w:
                        if (text[i] == 'ｗ')
                            count_w++;
                        else
                        {
                            mode = LoopMode.count_text;
                            count_text = text[i].ToString();
                        }
                        break;

                    case LoopMode.count_text:
                        if (text[i] == 'ｗ')
                        {
                            if (max_text < count_w)
                            {
                                result_text.Clear();
                                result_text.Add(count_text);
                                max_text = count_w;
                            }
                            else if (max_text == count_w)
                            {
                                result_text.Add(count_text);
                                max_text = count_w;
                            }
                            mode = LoopMode.count_w;
                            count_w = 1;
                        }
                        else
                            count_text = text[i].ToString() + count_text;
                        break;
                }
            }

            for (int i = result_text.Count - 1; i >= 0; i--)
                Console.WriteLine(result_text[i]);
        }
    }
}