#WA
list = gets.chomp.split("")
count_flag = 0
count = 0
list.each do |val|
	count_flag = 1 if val == "c"
	count += 1 if count_flag > 0
	count_flag += 1 if val == "w"
	break if count_flag == 3
end
puts count_flag == 3 ? count : -1