N = gets.split('')
flg_1 = 0
flg_2 = 0
count = 0

N.each do |w|
  count += 1 if flg_1 == 1
  if w == 'c'
    if flg_1 == 0
      flg_1 = 1
      count += 1
    end
  end

  if w == 'w'
    if flg_1 == 1
      if flg_2 == 0
        flg_2 = 1
        next
      else
        puts count
        exit
      end
    end
  end
end

puts -1