def main():

    s = list(input())
    cww_count = 0
    cww_length = []
    for i in range(len(s)):

        if s[i] == "c":
            cww_count += 1
            right = i
        elif s[i] == "w" and cww_count == 1:
            cww_count += 1
        elif s[i] == "w" and cww_count == 2:
            cww_count += 1
            left = i

            cww_length.append(left - right + 1)
            cww_count = 0
    if cww_length == []:
        print(-1)

    else:
        sorted_length = sorted(cww_length)
        print(int(sorted_length[0]))
    # デバッグ用
    # print(s)
    # print(cww_length)


if __name__ == "__main__":
    main()