题解 | #密码截取#

while True:
    try:
        s = input()
        length = len(s)
        max_len = 1
        for i in range(length - 1):
            for j in range(length, i + max_len, -1):
                if s[i] ==s[j-1] and s[i+1:j-1]==s[j-2:i:-1]:
                    max_len = len(s[i:j])
                    break
        print(max_len)
    except:
        break