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

def main():
    S = input()

    leng = len(S)
    kaibun1 = even(S, leng)
    kaibun2 = odd(S, leng)
    print(max(kaibun1, kaibun2))

def even(s, leng):
    ret = 0
    for i in range(leng - 2):
        cnt, l, r = 0, i - 1, i + 2
        if s[i] == s[i+1]:
            cnt = 2
        while 1:
            if s[l] == s[r]:
                cnt += 2
            ret = max(ret, cnt)
            if l > 0 and r < leng - 1:
                l -= 1; r += 1
            else:
                break
    return ret

def odd(s, leng):
    ret = 0
    for i in range(leng - 1):
        cnt, l, r = 1, i - 1, i + 1
        while 1:
            if s[l] == s[r]:
                cnt += 2
            ret = max(ret, cnt)
            if l > 0 and r < leng - 1:
                l -= 1; r += 1
            else:
                break
    return ret

main()