#include <cstdio>
#include <algorithm>

using namespace std;

#define maxn 1010

int n, m;
int sol;
int v[maxn][maxn];
int d[maxn][maxn][4];

int main()
{
  //  freopen("snake.in", "r", stdin);
    sol=-10001;

    scanf("%d", &n);

    for(int i=1; i<=n; ++i)
        for(int j=1; j<=n; ++j)
        {
            scanf("%d", &v[i][j]);
            sol=max(sol, v[i][j]);
        }

    for(int i=1; i<=n; ++i)
    {
        for(int j=1; j<=n; ++j)
        {
            d[i][j][0]=max(max(0, d[i][j-1][0]), d[i][j-1][3])+v[i][j];
            d[i][j][1]=max(max(0, d[i-1][j][1]), d[i-1][j][0])+v[i][j];
            d[i][j][3]=max(max(0, d[i-1][j][3]), d[i-1][j][2])+v[i][j];
        }
        for(int j=n; j; --j)
            d[i][j][2]=max(max(0, d[i][j+1][2]), d[i][j+1][1])+v[i][j];

        for(int j=1; j<=n; ++j)
            for(int k=0; k<4; ++k)
                sol=max(sol, d[i][j][k]);
    }

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

    return 0;
}