mod = 998244353


def main():
    import sys
    input = sys.stdin.readline

    S = input().rstrip('\n')
    N = len(S)

    G = [[0] * (N+1) for _ in range(N+1)]
    # odd
    for m in range(N):
        G[m][m+1] = 1
        for j in range(1, N + 1):
            if m - j < 0 or m + j >= N:
                break
            if S[m - j] == S[m + j]:
                G[m - j][m + j + 1] = 1
            else:
                break

    # even
    for m in range(1, N):
        for j in range(1, N+1):
            if m - j < 0 or m + j - 1 >= N:
                break
            if S[m - j] == S[m + j - 1]:
                G[m - j][m + j] = 1
            else:
                break

    ok = 1
    ng = N + 1
    mid = (ok + ng) // 2
    while ng - ok > 1:
        dp = [0] * (N+1)
        dp[0] = 1
        for i in range(N):
            if dp[i] == 0:
                continue
            for j in range(mid, N+1):
                if i + j >= N+1:
                    break
                if G[i][i+j]:
                    dp[i+j] = 1
        if dp[N]:
            ok = mid
        else:
            ng = mid
        mid = (ok + ng) // 2
    print(ok)


if __name__ == '__main__':
    main()