from collections import deque
S = input().rstrip()
lst = deque([(0, 0)])
MAX = 0
while len(lst) > 0:
    k, cnt = lst.popleft()
    c = S[k]
    for i in range(k, len(S)):
        if S[i] == c:
            for j in range(0, (i - k + 1) // 2):
                if S[k + j] != S[i - j]:
                    break
            else:
                if i != len(S) - 1 or cnt > 0:
                    MAX = max(MAX, i - k + 1)
                if i != len(S) - 1:
                    lst.append((i + 1, cnt + 1))
print(MAX)