题解 | #密码截取#

string = input()
string_len = len(string)
max = 0

for i in range(string_len):
    son = ''
    son += string[i]
    for j in string[i+1:]:
        son += j
        # print(son)
        if string[i] != j:
            continue
        elif son[::-1] == son:
            if len(son) > max:
                max = len(son)
           
print(max)