#include <iostream>

using namespace std;

const int NMAX= 50;

int v[NMAX+1][NMAX+1], col[NMAX+1][NMAX+1], lin[NMAX+1][NMAX+1];

void Suma_partiale( int N ) {
    for( int i=1; i<=N; i++ ) {
        for( int j=1; j<=N; j++ ) {
            col[i][j]= col[i][j-1] + v[j][i];
            lin[i][j]= lin[i][j-1] + v[i][j];
        }
    }
}


void rezolva( int N ) {
    int R= -(1<<30);
    for( int x1=1; x1<=N; x1++ ) {
        for( int y1=1; y1<=N; y1++ ) {
            int s;
            for( int x2= x1, y2= y1;  x2<=N && y2<=N;  x2++, y2++ ) {
                s= ( lin[x1][y2]-lin[x1][y1-1] ) + ( lin[x2][y2]-lin[x2][y1-1] ) + ( col[y1][x2]-col[y1][x1-1] ) + ( col[y2][x2]-col[y2][x1-1] ) - ( v[x2][y1]+v[x2][y2]+v[x1][y1]+v[x1][y2] );;
                if( s > R ) R= s;
            }
        }
    }
    cout << R << '\n';

}


int main()
{
    int N;
    cin >> N;
    for(int i=1; i<=N; i++) {
        for( int j=1; j<=N; j++ ) {
            cin >> v[i][j];
        }
    }
    Suma_partiale( N );
    rezolva( N );
    return 0;
}