S = list(input())
N = len(S)
ans = 0
for i in range(N):
    val = 1
    left = i - 1
    right = i + 1
    while left >= 0 and right <= N - 1:
        if S[left] == S[right]:
            val += 2
        left -= 1
        right += 1
    ans = max(ans, val)
print(ans)