import sys


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    s = input()
    n = len(s)
    d = [[1] * n for _ in range(n)]
    for l in range(1, n + 1):
        for i in range(n + 1 - l):
            if l != n and s[i:i + l] == s[i:i+l][::-1]:
                d[i][i + l - 1] = l
            for k in range(i, i + l - 1):
                d[i][i + l - 1] = max(d[i][i + l - 1], d[i][k], d[k + 1][i + l - 1])

    print(d[0][n - 1])


if __name__ == '__main__':
    ret = main()
    if ret is not None:
        print(ret)