#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second

using namespace std;

const int nmax = 1005;
const int inf = 1 << 30;

int n, i, j, sol, a[nmax][nmax], dp[nmax][nmax][4];

int main()
{
	// freopen("test.in", "r", stdin);
	// freopen("test.out", "w", stdout);

	scanf("%d", &n);

	for (i = 1; i <= n; i++)
		for (j = 1; j <= n; j++)
			scanf("%d", &a[i][j]);

	sol = -inf;

	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= n; j++)
		{
			dp[i][j][3] = a[i][j];

			if (i > 1)
			{
				dp[i][j][3] = max(dp[i][j][3], a[i][j] + dp[i - 1][j][3]);
				dp[i][j][3] = max(dp[i][j][3], a[i][j] + dp[i - 1][j][1]);
			}

			sol = max(sol, dp[i][j][3]);
		}

		for (j = 1; j <= n; j++)
		{
			dp[i][j][2] = a[i][j];

			if (i > 1)
			{
				dp[i][j][2] = max(dp[i][j][2], a[i][j] + dp[i - 1][j][2]);
				dp[i][j][2] = max(dp[i][j][2], a[i][j] + dp[i - 1][j][0]);
			}

			sol = max(sol, dp[i][j][2]);
		}

		for (j = 1; j <= n; j++)
		{
			dp[i][j][0] = a[i][j];

			if (j > 1)
				dp[i][j][0] = max(dp[i][j][0], a[i][j] + dp[i][j - 1][3]);

			if (j > 1)
				dp[i][j][0] = max(dp[i][j][0], a[i][j] + dp[i][j - 1][0]);

			sol = max(sol, dp[i][j][0]);
		}

		for (j = n; j >= 1; j--)
		{
			dp[i][j][1] = a[i][j];

			if (j < n)
				dp[i][j][1] = max(dp[i][j][1], a[i][j] + dp[i][j + 1][2]);

			if (j < n)
				dp[i][j][1] = max(dp[i][j][1], a[i][j] + dp[i][j + 1][1]);

			sol = max(sol, dp[i][j][1]);
		}
	}

	printf("%d\n", sol);

	return 0;
}