1 #include <bits/stdc++.h>
2 #define up(i,l,r) for(register int i = (l);i <= (r); i++)
3 #define dn(i,l,r) for(register int i = (l);i >= (r); i--)
4 #define ll long long
5 using namespace std;
6
7 const int N = 21000000;
8 int len,ans,r[N<<1];
9 char s[N],str[N<<1];
10
11 void init(){
12 len = strlen(s+1);
13 int k = -1;
14 str[++k] = '$';
15 up(i,1,len){
16 str[++k] = '#';
17 str[++k] = s[i];
18 }
19 str[++k] = '#';
20 len = k;
21 }
22
23 void Manacher(){
24 init();
25 int id = 1,mx = 1;
26 up(i,1,len-1){
27 if(mx > i) r[i] = min(r[id*2-i],mx-i);
28 else r[i] = 1;
29 while(str[i+r[i]] == str[i-r[i]]) ++r[i];
30 if(i+r[i] > mx){
31 mx = i+r[i];
32 id = i;
33 ans = max(ans,r[i]);
34 }
35 }
36 printf("%d",ans-1);
37 }
38
39 int main(){
40 scanf("%s",s+1);
41 Manacher();
42 return 0;
43 }
