#coding:utf-8

str=raw_input()
cww=str[str.index('c'):]

c_w=list(cww[:cww.index('w')+1])

s=[]
for i in cww[cww.index('w')+1:]:
	if 'w' not in i:
		s.append(i)
	else:
		s.append('w')
		break

if not c_w or not s or 'w' not in s:
	print -1
else:
	print len(c_w + s)