import java.util.*;
class Main {
    Scanner sc = new Scanner(System.in);
    int n;
    int maxn = 505;
    int[] dp = new int[maxn];

    void run() {
        n = sc.nextInt();
        Arrays.fill(dp, Integer.MIN_VALUE);
        dp[1] = sc.nextInt();
        for (int i = 2; i <= n; i++) {
            for (int j = i; j >= 1; j--) {      //从右到左
                dp[j] = Math.max(dp[j-1], dp[j]) + sc.nextInt();
            }
        }
        int res = Integer.MIN_VALUE;
        for (int i = 1; i <= n; i++) {
            res = Math.max(res, dp[i]);
        }
        System.out.println(res);
    }
    public static void main(String[] args) {
        Main m = new Main();
        m.run();
    }
}