#include <iostream>
#include <fstream>
#include <cmath>
#include <iomanip>
#include <vector>
#include <algorithm>

#define maxn 1010

using namespace std;

ifstream fin("test.in");
ofstream fout("test.out");

long long answer, dp[maxn][maxn][2], a[maxn][maxn], best[maxn][maxn][2];

int main()
{
    answer = -1000000000;

    int n;
    cin >> n;

    for (int i = 1; i <= n; ++i)
    {
        for (int j = 1; j <= n; ++j)
        {
            cin >> a[i][j];
        }
    }

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

    for (int i = 1; i <=n ; ++i)
    {
        for (int j = 1; j <= n; ++j)
        {
            dp[i][j][0]  = max(dp[i][j][0], best[i-1][j][1] + a[i][j]);
            dp[i][j][1]  = max(dp[i][j][1], best[i-1][j][0] + a[i][j]);
        }

        for (int j = 1; j < n; ++j)
        {
            dp[i][j+1][1] = max(dp[i][j+1][1], dp[i][j][1] + a[i][j+1]);
        }

        for (int j = n; j > 1; --j)
        {
            dp[i][j-1][0] = max(dp[i][j-1][0], dp[i][j][0] + a[i][j-1]);
        }

        for (int j =1; j <= n; ++j)
        {
            best[i][j][0] = max(best[i-1][j][0] + a[i][j], dp[i][j][0]);
            best[i][j][1] = max(best[i-1][j][1] + a[i][j], dp[i][j][1]);
            answer = max(answer, dp[i][j][0]);
            answer = max(answer, dp[i][j][1]);
        }
    }

    cout << answer;
}