题解 | #密码截取#

import sys

 
while 1:
    try:
        date=input()
       
        n=len(date)
        l=[]
        for i in range(n-1):            
            for x in range(n-1,0,-1):             
                if date[i]==date[x]:                                                  
                    if date[i:x+1]==date[i:x+1][::-1]:
                        l.append(len(date[i:x+1]))
                    else:
                        continue
                else:
                    continue
       
        print(sorted(l,reverse=True)[0])
    except:
        break