题解 | #密码截取#

s = input()
p = 0
for i in range(len(s)-1):
    for j in range(len(s)-1,i+1,-1):
        if s[i] == s[j] and s[i+1:j] == s[j-1:i:-1] and j-i+1 > p:
            p = j-i+1

print(p)