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

int main(){
    string s;
    cin >> s;
    int n = s.size();
    vector<vector<bool>> A(n + 1, vector<bool>(n + 1));
    vector<vector<int>> dp(n + 1, vector<int>(n + 1, -1));
    for(int i = 0; i < n; i++){
        A[i][i] = A[i][i + 1] = true;
    }
    for(int len = 2; len <= n; len++){
        for(int l = 0; l + len <= n; l++){
            int r = l + len;
            if(s[l] == s[r - 1] && A[l + 1][r - 1])A[l][r] = true;
        }
    }
    dp[0][0] = 0;
    for(int l = 0; l < n; l++){
        for(int j = 0; j < n; j++){
            if(dp[l][j] == -1)continue;
            for(int r = l + 1; r <= n; r++){
                if(A[l][r])dp[r][j + 1] = max(dp[r][j + 1], max(dp[l][j], r - l));
            }
        }
    }
    int ans = 0;
    for(int i = 2; i <= n; i++)ans = max(ans, dp[n][i]);
    cout << ans << '\n';
}