def ChiwawaFind(s) -> int:
    c = s.find("c")
    if c < 0:
        return -1
    sc = s[c:]
    w1 = sc.find("w")
    if w1 < 0:
        return -1
    sw1 = sc[w1 + 1:]
    w2 = sw1.find("w")
    if w2 < 0:
        return -1
    ans = sc[:w1 + w2 + 2]
    return len(ans)


s = input()
print(ChiwawaFind(s))