L = [str(x) for x in str(input())]
n = len(L)
c = 1

for m in range(0, n):
    for l in range(0, n - m + 1):
        M = L[l: l + m]
        N = M[::-1]
        if M == N and c < m:
            c = m

if n == 2:
    print('1')
else:
    print(c)