import sys
readline=sys.stdin.readline

S=readline().rstrip()
N=len(S)
ans=0
for i in range(N):
    for j in range(i+1,N+1):
        if (i,j)==(0,N):
            continue
        if S[i:j]==S[i:j][::-1]:
            ans=max(ans,j-i)
print(ans)