s = input()
l =[]
for i in range(len(s)):
    if s[i] == "c":
        for ii in range(i+1,len(s)):
            if s[ii] == "w":
                for iii in range(ii+1,len(s)):
                    if s[iii] == "w":
                        l.append(iii - i + 1)
if len(l) != 0:
    print(min(l))
else:
    print(-1)