import sys, math
sys.set_int_max_str_digits(0)

def f(S):
    N = len(S)
    longest = 0
    # 奇数長
    for i in range(N):
        for j in range(1, N):
            sub = 0
            l, r = i, i
            length = 1
            while True:
                # 確認
                if S[l] != S[r]:
                    break
                else:
                    if length > sub:
                        sub = length
                # 移動
                l -= j
                if l < 0:
                    break
                r += j
                if r >= N:
                    break
                length += 2
            longest = max(longest, sub)
            #print(i, j, sub)
    # 偶数長
    for i in range(N - 1):
        l, r = i, i + 1
        for j in range(1, N):
            sub = 0
            length = 2
            while True:
                # 確認
                if S[l] != S[r]:
                    break
                else:
                    if length > sub:
                        sub = length
                # 移動
                l -= j
                if l < 0:
                    break
                r += j
                if r >= N:
                    break
                length += 2

            longest = max(longest, sub)
            #print(i, j, sub)

    return longest

S = input()
print(f(S))