# -*- coding: utf-8 -*-

### O(N) ver. ###

s = input()
N = len(s)

mi = N + 1
w1 = w2 = N
for i in range(N)[::-1]:
    if s[i] == 'w':
        w1, w2 = i, w1
    if s[i] == 'c' and w2 < N:
        mi = min(mi, w2 - i + 1)

if mi != N + 1:
    print(mi)
else:
    print(-1)