#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    string s;
    cin >> s;
    int n = s.size();
    vector<vector<bool>> p(n, vector<bool>(n + 1, false));
    for (int i = 0; i < n; i++) {
        p[i][i + 1] = true;
        if (i < n - 1) {
            p[i][i + 2] = (s[i] == s[i + 1]);
        }
    }
    for (int len = 3; len <= n; len++) {
        for (int i = 0; i + len <= n; i++) {
            if (p[i + 1][i + len - 1] && s[i] == s[i + len - 1]) {
                p[i][i + len] = true;
            }
        }
    }
    vector<int> dp(n + 1, 0);
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < i; j++) {
            if (p[j][i]) {
                if (j == 0) {
                    dp[i] = max(dp[i], i);
                } else {
                    dp[i] = max(dp[i], min(dp[j], i - j));
                }
            }
        }
    }
    cout << dp[n] << '\n';
}