s = input()
t, r = [], []
for i in range(len(s)+1):
    for j in range(len(s)+1):
        if j-i > 0:
            r.append(s[i:j])
for i in r:
    if len(i) > 1 and i[:] == i[::-1]:
        t.append(len(i))

print(max(t))