#include <bits/stdc++.h>
using namespace std;
#define rep(i, l, r) for (int i = (int)(l); i < (int)(r); i++)
#define rrep(i, r, l) for (int i = (int)(r); i > (int)(l); i--)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()

void solve() {
    const int MAX = 5005;
    string s;
    cin >> s;
    const int n = s.size();
    vector<int> dp(n + 1, 0);
    vector<vector<bool>> kaibun(n + 1, vector<bool>(n + 1, false));
    
    rep(i, 0, n) {
        kaibun[i][i + 1] = true;
        kaibun[i][i] = true;
    }

    rep(len, 2, n + 1) {
        rep(l, 0, n - len + 1) {
            int r = l + len;
            if (kaibun[l + 1][r - 1] && s[l] == s[r - 1]) {
                kaibun[l][r] = true;
            }
        }
    }

    dp[0] = MAX;
    rep(i, 0, n) {
        rep(j, i + 1, n + 1) {
            if (kaibun[i][j]) {
                dp[j] = max(dp[j], min(j - i, dp[i]));
            }
        }
    }

    cout << dp[n] << '\n';
}

int main() {
    int q = 1;
    // cin >> q;
    while (q--) {
        solve();
    }
}