# coding: utf-8
S = list(input())

start_index = S.index("c")

if start_index == -1:
    print(-1)
else:
    del S[:start_index]

indexes = [i for i, x in enumerate(S) if x == 'w']

if len(indexes) < 2:
    print(-1)
else:
    print(indexes[1] + 1 )