题解 | #密码截取#

x = input()

lx= len(x)
maxodd = [1]*lx
maxeven= [0]*lx
for i in range(lx):
    #奇数回文串
    low = i-1 
    high = i+1
    maxodd[0] = 1
    while (low>=0 and high<=lx-1) and x[low] == x[high]:
        maxodd[i] +=2
        low -=1
        high +=1
    
    #偶数回文串
    low = i
    high = i+1
 
    while (low>=0 and high<=lx-1) and x[low] == x[high]:
        maxeven[i] +=2
        low -=1
        high +=1

print(max(max(maxodd),max(maxeven)))