S = input()
L = len(S)
ans = 0
for i in range(L):
    j = 1
    tmp = 1
    while 0 <= i - j and i + j < L:
        if S[i - j] == S[i + j]:
            tmp += 2
        j += 1
    ans = max(ans, tmp)

for i in range(L):
    j = 0
    tmp = 0
    while 0 <= i - j and i + j + 1 < L:
        if S[i - j] == S[i + j + 1]:
            tmp += 2
        j += 1
    ans = max(ans, tmp)
print(ans)