import sys
input = sys.stdin.readline

S=list(input().strip())
DP=[0]*(len(S)+1)
DP[0]=1<<60
for i in range(len(S)):
    for j in range(i,len(S)):
        if S[i:j+1]==S[i:j+1][::-1]:
            DP[j+1]=max(DP[j+1],min(DP[i],j+1-i))

print(DP[-1])