#!/usr/bin/env python3
#fileencoding: utf-8

count = 0
mi = 100
w_cnt = 0
for i in input()[::-1]:
    if i == "w":
        count += 1
        w_cnt += 1
    elif w_cnt >= 2 and i == "c":
        cww = True
        count += 1
        if mi > count:
            mi = count
        count = 0
        w_cnt = 0
    else:
        if count >= 1:
            count += 1
        else:
            count = 0

print(mi if cww else -1)