题解 | #坐标移动#

import sys
#对字符串中的每一个字符遍历，首先判断是奇数回文串还是偶数回文串，再向两边拓展，判断并记录回文串的长度

def action(mm):
    maxx = 0
    for i in range(1,len(mm)-1):
        if mm[i] == mm[i - 1]:
            j = 1
            while i + j <= len(mm)-1 and i-1-j >= 0 :
                if mm[i+j] == mm[i-1-j]:
                    if maxx < 2*j + 2:
                        maxx = 2*j + 2

                    j += 1
                else:
                    
                    break

        if mm[i] == mm[i + 1]:
            j = 1
            while i + 1 + j <= len(mm)-1 and i - j >= 0 :
                if mm[i + 1 + j] == mm[i - j]:
                    if maxx < 2*j + 2:
                        maxx = 2*j + 2

                    j += 1
                else:
                    break
        if mm[i] == mm[i + 1] and mm[i] == mm[i - 1]:
            j = 1
            while i + 1 + j <= len(mm)-1 and i-1-j >= 0 :
                if mm[i+1+j] == mm[i-1-j]:
                    if maxx < 2*j + 3:
                        maxx = 2*j + 3

                    j += 1
                
                else:
                    
                    break
        if mm[i] != mm[i + 1] and mm[i] != mm[i - 1]:
                j = 1
                while i + j <= len(mm)-1 and i-j >= 0 :
                    if mm[i+j] == mm[i-j]:
                        if maxx < 2*j + 1:
                            maxx = 2*j + 1
                        j += 1
                    else:
                        break
    print(maxx)
for i in sys.stdin:
    action(i.strip("\n"))