strs = gets.chomp.to_s.split("")
count = 0
c_flag = false
w1_flag = false
w2_flag = false

strs.each do |str|
	c_flag = true if str === "c"
	if c_flag
		count += 1
		if str === "w"
			w1_flag = true
			c_flag = false
			next
		end
	end

	if w1_flag
		count += 1
		w2_flag = true if str === "w"
	end
	break if w2_flag
end

puts w2_flag ? count : -1