#include <iostream>
#include <fstream>
using namespace std;
//ifstream fin("royfloyd.in");
#define MAX 54

int a[MAX][MAX], s1[MAX][MAX], s2[MAX][MAX];

int main()
{
    int n, i, j, s, i1, j1, t;
    cin>>n;
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
        {
            cin>>a[i][j];
        }
    }
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
        {
            s1[i][j]=a[i][j]+s1[i-1][j];
            s2[i][j]=a[i][j]+s2[i][j-1];
        }
    }
    s=1<<31;
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=n;j++)
        {
            for(i1=i;i1<=n;i1++)
            {
                for(j1=j;j1<=n;j1++)
                {
                    if(i1-i!=j1-j)
                        continue;
                    t=(s2[i1][j1]-s2[i1][j-1])+(s2[i][j1]-s2[i][j-1])+(s1[i1-1][j1]-s1[i][j1])+(s1[i1-1][j]-s1[i][j]);

                    if(i1==i)
                    {
                        t=s2[i][j1]-s2[i][j-1];
                    }
                    else if(j==j1)
                    {
                        t=s1[i1][j]-s1[i-1][j];
                    }

                    s=max(s, t);
                }
            }
        }
    }
    cout<<s<<"\n";

}