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