#include <cstdio>
#include <cstdlib>
#include <algorithm>
#define MAX 1010

using namespace std;

typedef long long ll;

int N;
int val[MAX][MAX];
ll dp[MAX][MAX];

int main(){
	while(scanf("%d", &N) && N != 0){
		for(int i = 0; i < MAX; i++)
			for(int j = 0; j < MAX; j++)
				dp[i][j] = 0;
		for(int i = 0; i < N; i++)
			for(int j = 0; j <= i; j++){
				scanf("%d", &val[i-j+1][j+1]);
			}
		N++;
		for(int i = 1; i < N; i++){
			for(int j = 1; j <= N-i; j++)
				dp[i][j] = val[i][j] + dp[i-1][j] + dp[i][j-1] - dp[i-1][j-1];
		}
		ll resp = 0;
		for(int i = 1; i < N; i++){
			for(int j = N-i; j > 0; j--){
				ll col = dp[i][j] - dp[i][j-1];
				//printf ("%lld\n", col);
				resp = max(resp, dp[i][j] + dp[i-1][j+1]);
				dp[i][j] = max( max(col, col+dp[i-1][j+1]), max(dp[i-1][j], dp[i][j+1] + col));
			}
		}
		printf("%lld\n", resp);
	}
	return 0;
}