题解 | #最长回文子串#

ipt = input()
def len_longestsubpalin(s):
    
    #search from the longest sub str(itself) to a single char
    for lensub in range(len(s), 0, -1):
        
        # i is the location of this sub str
        for i in range(0, len(s) - lensub +1):
            
            # the first returned val must be the longest sub palindrome str
            if s[i:i+lensub] == s[i:i+lensub][::-1]:
                return lensub

print(len_longestsubpalin(ipt))