S = input()
ans = 0

def check(T):
    return T == T[::-1]
for i in range(len(S)):
    for j in range(i,len(S)):
        if check(S[i:j+1]):
            if j - i + 1 < len(S) and j - i + 1 > ans:
                ans = j - i + 1
print(ans)