#include <stdio.h>
#define NMax 55

int n;
int a[NMax][NMax];

int up[NMax][NMax], st[NMax][NMax];

int sum(int x1, int y1, int x2, int y2) {
	int ret = 0;

	ret += st[x1][y2] - st[x1][y1-1];
	if (x2 > x1) {
		ret += st[x2][y2] - st[x2][y1-1];
	}

	if (x2 - x1 > 1) {
		ret += up[x2-1][y1] - up[x1][y1];
		if (y2 > y1) {
			ret += up[x2-1][y2] - up[x1][y2];
		}
	}
	return ret;
}

int main() {

	//freopen("m.in", "rt", stdin);

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

			up[i][j] = up[i-1][j] + a[i][j];

			st[i][j] = st[i][j-1] + a[i][j];
		}
	}
	int maxx  = a[1][1];

	for (int x1 = 1; x1 <= n; x1++) {
		for (int y1 = 1; y1 <= n; y1++) {

			for (int x2 = x1; x2 <= n; x2++) {
				//for (int y2 = y1; y2 <= n; y2++) {
				int y2 = y1 + x2 - x1;

				if (y2 > 0 && y2 <= n) {


					int ssum = sum(x1, y1, x2, y2);
					if (ssum > maxx) {
						maxx = ssum;
					}
				}
			}
		}
	}

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

	
	return 0;
}