#include<cstdio>

 #include<cstring>

 #define min(a,b) (a)>(b)?(b):(a)

 #define max(a,b) (a)>(b)?(a):(b)

 const int maxn = ;//字符串长度

 struct Manacher{

     char str[maxn<<];

     int p[maxn<<],len,mx,id,tl,ans,i;

     //bool pre[maxn],suf[maxn];//前(后)缀(前(后)p[i]-1个字符)是回文串

     //void init(int len){for(int i=0;i<=len;i++)suf[i]=0,pre[i]=0;}

     int maxlen(char *s){

         len=strlen(s),mx=,id=,tl=,str[tl++]='$',str[tl++]='#';

         for(i=;i<len;i++)str[tl++]=s[i],str[tl++]='#';

         for(i=,str[tl]=,ans=;i<tl;i++){

             p[i]=mx>i?min(p[(id<<)-i],mx-i):;

             while(str[i-p[i]]==str[i+p[i]])p[i]++;

             if(i+p[i]>mx)mx=i+p[i],id=i;

             ans=max(ans,p[i]);

             //if(i-p[i]==0)pre[p[i]-1]=true;

             //if(i+p[i]==len*2+2)suf[p[i]-1]=true;

         }

         return ans-;

     }

 }M;

 char s[maxn];

 int main(){

     while(~scanf("%s",s)){

         printf("%d\n",M.maxlen(s));

     }

     return ;

 }