s=raw_input()
l=[]
for i in range(len(s)):
	if s[i]=="c":
		w=s.find("w",i)
		if w>0:
			w=s.find("w",w+1)
			if w>0:
				l+=[w-i+1]
if len(l)==0:
	print -1
else:
	print min(l)