N = gets.split('')
watch = []
count = 0

N.each do |w|
  count += 1 unless watch[0].nil?
  if w == 'c'
    watch[0] = 1
    count += 1
  end
  if w == 'w' && watch[0] == 1 && watch[1] != 1
    watch[1] = 1
    next
  end
  if w == 'w' && watch[1] == 1
    puts count
    exit
  end
end

puts -1