#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    string s;
    cin >> s;
    string s2 = "";
    s2 += s[0];
    for (int i = 1; i < s.size(); i++) {
        s2 += " ";
        s2 += s[i];
    }
    int ans = 0;
    for (int i = 0; i < s2.size(); i++) {
        int cnt = (s2[i] != ' ');
        for (int j = 1; ; j++) {
            if (i - j < 0 || i + j >= s2.size()) break;
            cnt += (s2[i - j] == s2[i + j] && s2[i - j] != ' ') * 2;
        }
        ans = max(ans, cnt);
    }
    cout << ans << endl;
    return 0;
}