S=raw_input()
c=[]
w=[]
for i in range(len(S)):
	if S[i]=='c': c.append(i)
	if S[i]=='w': w.append(i)
ans=10000
for i in range(len(w)-1):
	for j in c:
		if j<w[i]:
			ans=min(ans,w[i+1]-j+1)

if ans==10000: print -1
else: print ans