using System;
using System.Collections.Generic;
using System.Linq;

class Warota : IComparable<Warota>
{
    public string Word;
    public int Len;

    public Warota(string word, int len)
    {
        Word = word;
        Len = len;
    }

    public int CompareTo(Warota w)
    {
        return Len.CompareTo(w.Len);
    }
}

class Program
{
    static void Main()
    {
        string s = Console.ReadLine();
        var w = new List<Warota>();
        string buf = "";
        int wcnt = 0;

        s = new string(s.Reverse().ToArray()) + "ｗ";

        foreach (var c in s)
        {
            if (c != 'ｗ')
            {
                buf = buf.Insert(0, c.ToString());
            }
            else
            {
                if (buf != "")
                {
                    w.Add(new Warota(buf, wcnt));
                    wcnt = 0;
                }
                buf = "";
                wcnt++;
            }
        }

        w.Reverse();

        foreach (var ans in w)
        {
            if (ans.Len == w.Max().Len)
            {
                Console.WriteLine(ans.Word);
            }
        }
    }
}