#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s;
    cin >> s;
    int n = s.size();
    vector<vector<bool>> dp2(n + 1, vector<bool>(n + 1));
    for(int i = 0; i < n; i++)dp2[i][i] = dp2[i][i + 1] = true;
    for(int len = 2; len <= n; len++){
        for(int l = 0; l + len <= n; l++){
            if(s[l] == s[l + len - 1] && dp2[l + 1][l + len - 1])dp2[l][l + len] = true;
        }
    }
    vector<int> dp(n + 1, -1);
    dp[0] = 1 << 30;
    for(int i = 0; i < n; i++){
        for(int j = i + 1; j <= n; j++){
            if(dp2[i][j]) dp[j] = max(dp[j], min(dp[i], j - i));
        }
    }
    cout << dp[n] << '\n';
}