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

count = 0
mi = 100
w_2 = False
cww = False
for i in input():
    if i == "c":
        count = 1
    elif count >= 1 and i == "w" and w_2 == False:
        count += 1
        w_2 = True
    elif w_2 and i == "w":
        cww = True
        count += 1
        if mi > count:
            mi = count
        count = 0
    else:
        if count >= 1:
            count += 1
        else:
            count = 0
print(mi if cww else -1)