S = list(input())
candidate = []
for i in range(len(S)) :
    if S[i] == "c" :
        for j in range(i+1,len(S)) :
            if S[j] == "w" :
                for k in range(j+1,len(S)) :
                    if S[k] == "w" :
                        candidate.append(k-i+1)
if len(candidate) >= 1 :
    print(min(candidate))
else :
    print(-1)