# -*- coding: utf-8 -*-
S = raw_input()
Slist = list(S)
N = len(Slist)
lencww = 1000
for i in range(0, N):
    if Slist[i] == "c":
        flag = 0
        for j in range(i, N):
            if flag % 2 == 0 and Slist[j] == "w":
                flag += 1
            elif flag % 2 == 1 and Slist[j] == "w":
                tmp = j - i + 1
                if tmp < lencww:
                    lencww = tmp
                    continue
if lencww != 1000:
    print lencww
else:
    print -1