//
//  main.cpp
//  less-1
//
//  Created by Kadir Kadyrov on 28.03.2021.
//

#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int n;
    cin >> n;
    int a[n][n], b[n][n];

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cin >> a[i][j];
            b[i][j] = 0;
        }
    }

    b[0][0] = a[0][0];

    for (int i = 1; i < n; i++) {
        b[0][i] = b[0][i - 1] + a[0][i];
    }

    for (int i = 1; i < n; i++) {
        b[i][0] = b[i - 1][0] + a[i][0];
    }

    for (int i = 1; i < n; i++) {
        for (int j = 1; j < n; j++) {
            if (b[i - 1][j] > b[i][j - 1]) {
                b[i][j] = a[i][j] + b[i - 1][j];
            } else {
                b[i][j] = a[i][j] + b[i][j - 1];
            }
        }
    }

    cout << b[n - 1][n - 1] << endl;
}

/*
 4
 2 3 -5 8
 0 7 -10 6
 -3 7 3 1
 -10 4 2 5
 */