S = input()
ans = 0

if len(S) == 1:
    ans = 1
else:
    for i in range(1, len(S)):
        cnt = 0
        j = 0
        while i + j < len(S) and i - j - 1 >= 0:
            if S[i - j - 1] == S[i + j]:
                cnt += 2
            else:
                break
            j += 1
        ans = max(ans, cnt)

        cnt = 1
        j = 1
        while i + j < len(S) and i - j >= 0:
            if S[i - j] == S[i + j]:
                cnt += 2
            else:
                break
            j += 1
        ans = max(ans, cnt)

print(ans)