#include <bits/stdc++.h>

using namespace std;

const int N = 3e5;

char s[N], str[N];
int len1, len2, id, mx, ans, p[N];

void init() { // 翻倍
    str[0] = '$';
    str[1] = '#';
    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() {
    id = 0, mx = 0;
    for(int i = 1; i < len2; i++) {
        if(i < mx) p[i] = min(p[2*id-i], mx - i); // 对称点的回文半径 和 i到mx之间的距离
        else p[i] = 1;
        while(str[i+p[i]] == str[i-p[i]]) p[i]++; // 暴力匹配
        if(i + p[i] < mx) { // 更新id和mx
            mx = i;
            mx = i + p[i];
        }
    }
}

int main() {
    cin >> s;
    len1 = strlen(s);
    init();
    manacher();
    for(int i = 0; i < len2; i++) ans = max(ans, p[i]);
    cout << ans - 1 << endl;
    return 0;
}