S = input()

i = 0
c = 1
cww = ["c", "w", "w"]

ans = []

for s in S:
    c += 1
    if s == cww[i]:
        if i == 0:
            c = 1
        if i == 2:
            ans.append(c)
        i = (i + 1) % len(cww)

print(min(ans) if len(ans) > 0 else -1)