#include <iostream>

using namespace std;

int v[60][60], v2[60][60], v3[60][60];

int calcSum(int i, int j, int i2, int j2) {
	int sum = 0;
	//if (i2-i != j2-j) return -5000000;
	
	sum = v2[i2][j2] - v2[i][j2];
    if (j!=j2) sum += v2[i2][j] - v2[i][j];
	sum += v3[i2][j2] - v3[i2][j]; 
	if (i!=i2) sum += v3[i][j2] - v3[i][j];
	sum += v[i][j];
	if (i != i2 && j != j2) sum -= v[i2][j2];
	
	return sum;
}

int main() {
	int n,nr,r=-5000000,i,j,i2,j2;
	cin>>n;
	
	for (i=1;i<=n;i++)
		for (j=1;j<=n;j++) {
			cin>>v[i][j];
			if (i!=1) {
				v2[i][j] = v2[i-1][j];
			}
			v2[i][j] += v[i][j];

			if (j!=1) {
				v3[i][j] = v3[i][j-1];
			}
			v3[i][j] += v[i][j];
		}
			
		
    for (i=1;i<=n;i++)
		for (j=1;j<=n;j++)
			for (i2=i;i2<=n;i2++)
				for (j2=j;j2<=n;j2++) {
					nr = calcSum(i,j,i2,j2);
					if (nr > r) r = nr;
				}
	
	cout<<r;
	
	return 0;
}