import java.util.*;
class Main {
    public static int n = 501;

    public static void main(String[] args) {
        int[][] triangle = new int[n][n];
        Scanner sc = new Scanner(System.in);
        int rows = sc.nextInt();
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < i + 1; j++)
                triangle[i][j] = sc.nextInt();
        }
        int[] dp = new int[n];
        for (int r = rows - 1; r >= 0; r--) {
            for (int i = 0; i < n - 1; i++)
                dp[i] = Math.max(dp[i], dp[i + 1]) + triangle[r][i];
        }

        System.out.println(dp[0]);
    }
}