from sys import stdin, stdout
input = lambda: stdin.readline().rstrip()
write = stdout.write

def main():
    S = input()

    leng = len(S)
    ans = 0
    for i in range(1, leng - 1):
        cnt, l, r = 1, i - 1, i + 1
        while 1:
            if S[l] == S[r]:
                cnt += 2
            elif S[i] == S[l] or S[i] == S[r]:
                cnt = max(2, cnt)
            ans = max(ans, cnt)
            if l > 0 and r < leng - 1:
                l -= 1; r += 1
            else:
                break
    print(ans)

main()