#include <iostream>
#define INF 1000100000
using namespace std;
int n, mat[1010][1010], sol;
int best[4][1010][1010];

/// 0 = L -> 0, 2
/// 1 = R -> 1, 3
/// 2 = LD -> 2, 1
/// 3 = RD -> 3, 0

int main()
{
    //freopen("B.in", "r", stdin);
    int i, j;
    cin >> n;
    for(i = 1; i <= n; ++i)
        for(j = 1; j <= n; ++j)
            cin >> mat[i][j];
    for(i = 0; i <= n + 1; ++i)
        for(j = 0; j <= n + 1; ++j)
            best[0][i][j] = best[1][i][j] = best[2][i][j] = best[3][i][j] = -INF;

    for(i = 1; i <= n; ++i)
    {
        for(j = 1; j <= n; ++j)
            best[0][i][j] = best[1][i][j] = best[2][i][j] = best[3][i][j] = mat[i][j];
        for(j = 1; j <= n; ++j)
        {
            best[2][i][j] = max(best[2][i][j], best[2][i - 1][j] + mat[i][j]);
            best[2][i][j] = max(best[2][i][j], best[0][i - 1][j] + mat[i][j]);
            best[3][i][j] = max(best[3][i][j], best[3][i - 1][j] + mat[i][j]);
            best[3][i][j] = max(best[3][i][j], best[1][i - 1][j] + mat[i][j]);
        }
        for(j = 1; j <= n; ++j)
        {
            best[0][i][j] = max(best[0][i][j], best[0][i][j - 1] + mat[i][j]);
            best[0][i][j] = max(best[0][i][j], best[3][i][j - 1] + mat[i][j]);
        }
        for(j = n; j > 0; --j)
        {
            best[1][i][j] = max(best[1][i][j], best[1][i][j + 1] + mat[i][j]);
            best[1][i][j] = max(best[1][i][j], best[2][i][j + 1] + mat[i][j]);
        }
    }
    sol = -INF;
    for(i = 1; i <= n; ++i)
        for(j = 1; j <= n; ++j)
        {
            sol = max(sol, max(best[0][i][j], best[1][i][j]));
            sol = max(sol, max(best[2][i][j], best[3][i][j]));
        }
    cout << sol << "\n";
    return 0;
}