import java.util.Scanner;public class Main {    public static int[][] rewards;    public static int[][] best;    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        int n = scanner.nextInt();        rewards = new int[n + 1][n + 1]; //下标均从1开始        best = new int[n + 1][n + 1];         for (int i = 1; i <= n; i++) {            for (int j = 1; j <= i; j++) {                rewards[i][j] = scanner.nextInt();            }        }        int ans = Integer.MIN_VALUE;        for (int i = 1; i <= n; i++) {            for (int j = 1; j <= i; j++) {                best[i][j] = Math.max(best[i - 1][j - 1], best[i - 1][j])                        + rewards[i][j];                if (ans < best[i][j]) {                    ans = best[i][j];                }            }        }        System.out.println(ans);    }}