1 /*************************************************************************
 2     > File Name: hdu_3068.cpp
 3     > Author: Stomach_ache
 4     > Mail: sudaweitong@gmail.com
 5     > Created Time: 2014年08月04日 星期一 18时44分05秒
 6     > Propose: hdu3068, poj3974
 7  ************************************************************************/
 8 // Manacher O(n)
 9 #include <cmath>
10 #include <string>
11 #include <cstdio>
12 #include <fstream>
13 #include <cstring>
14 #include <iostream>
15 #include <algorithm>
16 using namespace std;
17 
18 const int maxn = 100005;
19 char s[maxn], str[maxn<<1];
20 int p[maxn<<1], n;
21 
22 void Manacher() {
23       n = strlen(s);
24     str[0] = ‘$‘;
25     str[1] = ‘#‘;
26     for (int i = 0; i < n; i++) {
27         str[i*2+2] = s[i];
28           str[i*2+3] = ‘#‘;
29     }
30     n = n * 2 + 2;
31     str[n] = 0;
32 
33     int mx = 0;
34     int id;
35     for (int i = 1; i < n; i++) {
36           if (mx > i) p[i] = min(p[2*id-i], mx - i);
37         else p[i] = 1;
38         for ( ;str[i-p[i]] == str[i+p[i]]; p[i]++);
39         if (p[i] + i > mx) {
40               mx = p[i] + i;
41             id = i;
42         }
43     }
44 }
45 
46 void solve() {
47     Manacher();
48     int ans = 0;
49     for (int i = 0; i < n; i++) ans = max(ans, p[i]);
50     printf("%d\n", ans - 1);
51 }
52 
53 int main(void) {
54       while (~scanf("%s", s)) {
55           solve();
56     }
57 
58     return 0;
59 }