a = gets.chomp.split("")
b = []
count = 0
a.length.times do |i|
  count += 1 if b.include?("c")
  if a[i] == "c" && b.empty?
    b.push("c")
    count += 1
  elsif a[i] == "w" && b.include?("c") && b.count("w") < 2
    b.push("w")
  end
  break if b.count("w") == 2
end
puts b.count("w") == 2 ? count : -1