from itertools import combinations

S=list(map(str, input()))
N=len(S)
L=[i for i in range(N+1)]

ans=0
for i in combinations(L,2):
    l, r = i[0],i[1]
    if l == 0 and r == N:
        continue

    if S[l:r] == S[l:r][::-1]:
        ans = max(ans, r-l)

print(ans)