class Yukicoder
  def initialize
    s = gets.chomp

    word = ""
    temp = ""
    list = Hash.new(0)
    w_count = 0

    s.sub!(/^ｗ+/,'')

    s.chars do |ch|
      if ch == 'ｗ'
        if w_count == 0
          temp = word.dup 
        end

        w_count += 1
        list[temp] += 1

        word = ""
      else
        w_count = 0
        word += ch
      end
    end

    list = list.sort_by{|k,v| -v}.to_h
    max_val = list.first[1]

    puts list.select{|k,v| max_val == v}.keys
  end
end

Yukicoder.new