S = input()
cww_col = ["c", "w", "w"]
t = 0
min_l = 999
cnt_l = 0
for Si in S:
    cnt_l += 1
    if cww_col[t] == Si:
        if t == 0:
            cnt_l = 1
        if t == len(cww_col)-1:
            if cnt_l < min_l:
                min_l = cnt_l
            cnt_l = 1
            t = 0
            continue
        t += 1

if min_l == 999:
    print(-1)
else:
    print(min_l)