#!/usr/bin/python
# -*- coding: utf-8 -*-

str = raw_input()
flag = 0
count = 0
for i in str:
	if i == "c" and flag == 0:
		flag = 1
		count += 1
	elif i == "w" and flag == 1:
		flag = 2
		count += 1
	elif i == "w" and flag == 2:
		count += 1
		print count
		exit()
	elif i != "c" and i != "w" and flag > 0:
		count += 1
	else:
		flag = 0
		count = 0
print '-1'