#include <iostream>
#include <vector>
using namespace std;

int main () {
    int n;
    cin >> n;
    vector<vector<int> > M = vector<vector<int> >(n, vector<int>(n));
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> M[i][j];
        }
    }

    vector<int> dist = vector<int>(n);
    dist[0] = 0;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < i; ++j) {
            M[i][j] = M[j][i];
            if (dist[j] + M[j][i] > dist[i-j]) dist[j] = dist[j] + M[j][i];
            else dist[j] = dist[i-j];
        }
    }

    int max = 0;
    for (int i = 0; i < n; ++i) {
        if (dist[i] > max) max = dist[i];
    }

    cout << max << endl;
}