import bisect
s=input()
clist = []
wlist = []
ans = 10**12
for i in range(len(s)):
	if s[i] == "c":
		clist.append(i)
	elif s[i] == "w":
		wlist.append(i)
for i in clist:
	a = bisect.bisect_right(wlist, i)
	if len(wlist) <= a+1:
		break
	else:
		ans = min(wlist[a+1]-i+1, ans)
if ans != 10**12:
	print(ans)
else:
	print(-1)