s = list(input())
cww = []
ans = []

s.reverse()
w = []
for i in range(len(s)):
    if s[i]=="w":
        w.append(i)
    elif s[i]=="c":
        if len(w)>1:
            ans.append(i-w[-2])
print(-1 if ans==[] else min(ans)+1)