import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
	public static void main (String[] args)
	{
		Scanner in = new Scanner(System.in);
		int[][] s = new int[1001][1001];
		while (in.hasNextInt()) 
		{
			int n = in.nextInt();
			int ans = 0;
			if(n==0)
			{
				break;
			} else {
				for (int i = 1; i <= n; i++) 
				{
					for (int j = 1; j <= i; j++) 
					{
						s[i][j] = in.nextInt();
						s[i][j] += s[i - 1][j];
					}
				}
				for (int j = 1; j <= n; j++)
				{
					for (int i = j; i <= n; i++) 
					{
						s[i][j] += s[i - 1][j - 1];
					}
					for (int i = n - 1; i >= j; i--) {
						s[i][j] = Math.max(s[i][j], s[i + 1][j]);
					}
				}
				for (int i = 1; i <= n; i++) {
					ans = Math.max(ans, s[i][i]);
				}
				System.out.println(ans);
			}
		}
	}
}