import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
s = input()
n = len(s)

dp = [[0 for j in range(n+1)]for i in range(n)]

for i in range(n):
    dp[i][i+1] = 1
    dp[i][i] = 1

for d in range(2,n+1):
    for i in range(n-d+1):
        j = i + d
        if s[i] == s[j-1]:
            dp[i][j] = dp[i+1][j-1]

ans = [0] * (n+1)
ans[0] = 10**9

for i in range(n):
    for j in range(i+1, n+1):
        if dp[i][j]:
            ans[j] = max(ans[j], min(ans[i], j-i))

print(ans[n])