s = input()
n = len(s)

ans = 1
for l in range(n):
    for r in range(l + 1, n):
        m = r - l + 1
        a = 0
        for i in range(m // 2):
            if s[l + i] != s[r - i]:
                a += 2
        ans = max(ans, m - a)

print(ans)