#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5+10;
char s[maxn], str[maxn];
int p[maxn];//回文半径
int len1, len2;
void init(){
    str[0] = '?';
    str[1] = '#';//使之变成奇数长度的字符串
    for(int i=0; i<len1; i++){
        str[i*2+2] = s[i];
        str[i*2+3] = '#';
    }
    len2 = len1*2+2;
    str[len2] = '$';
}
void manacher(){
    int mid = 0, mx = 0;
    for(int i=1; i<len2; i++){//mx是最右边的开区间
        if(mx>i) p[i] = min(p[2*mid-i], mx-i);
        else p[i] = 1;
        for(; str[i+p[i]] == str[i-p[i]]; p[i]++);
        if(p[i]+i>mx){
            mx = p[i]+i;
            mid = i;
        }
    }
}
int main()
{
    while(~scanf("%s", s)){
        len1 = strlen(s);
        init();
        manacher();
        int ans = 0;
        for(int i=1; i<len2; i++){
            ans = max(ans, p[i]);
        }
        //#b#a # a#b#，偶数
        //#a#, 奇数  他们的长度都是回文半径-1
        cout<<ans-1<<endl;
    }
    return 0;
}