S = input()
L = len(S)
res = 0
for i in range(L):
    tmp = 1
    for j in range(min(i, L - 1 - i)):
        if S[i - j - 1] == S[i + j + 1]:
            tmp += 2
    res = max(res, tmp)
for i in range(L - 1):
    tmp = 0
    for j in range(min(i + 1, L - 1 - i)):
        if S[i - j] == S[i + j + 1]:
            tmp += 2
    res = max(res, tmp)
print(res)