#include <iostream>
#include <algorithm>
#define NMAX 55

using namespace std;

int A[NMAX][NMAX],N,MAX=-99999;

void read()
{
    cin>>N;
    for (int i=1;i<=N;i++)
        for (int j=1;j<=N;j++)
        {
            cin>>A[i][j];
            if (A[i][j]>MAX) MAX=A[i][j];
        }
}

int calc(int x1,int y1,int x2,int y2)
{
    int sum=0;
    for (int i=x1;i<=x2;i++)
        sum=sum+A[i][y1]+A[i][y2];

    for (int j=y1;j<=y2;j++)
        sum=sum+A[x1][j]+A[x2][j];

    sum=sum-abs(A[x1][y1])-abs(A[x2][y1])-abs(A[x2][y2])-abs(A[x1][y2]);

    return sum;
}

void solve()
{
    int i,j,k;

    for (i=1;i<N;i++)
        for (j=1;j<N;j++)
            for (k=1;i+k<=N && j+k<=N;k++)
                if (calc(i,j,i+k,j+k)>MAX) MAX=calc(i,j,i+k,j+k);

    cout<<MAX;
}

int main()
{
    read();
    if (N==1) cout<<A[1][1];
    else
        solve();

    return 0;
}