#include<stdio.h>

int a[55][55],l[55][55],c[55][55];
int main()
{

	int n;
	scanf("%d", &n);
	for (int i = 1; i <= n;++i)
	for (int j = 1; j <= n; ++j)
	{
		scanf("%d", &a[i][j]);
	}
	int minim = -5000;
	for (int i = 1; i <= n; ++i)
	{
		for (int j = 1; j <= n; ++j)
		{
			l[i][j] = l[i][j - 1] + a[i][j];
			c[i][j] = c[i - 1][j] + a[i][j];
		}
	}
	for (int i = 1; i <= n; ++i)
	{
		for (int j = 1; j <= n; ++j)
		{
			for (int t = j; t <= n; ++t)
			{
				if (minim < l[i][t] - l[i][j - 1])
					minim = l[i][t] - l[i][j - 1];
				if (minim < c[t][i]-c[j-1][i])
					minim = c[t][i] - c[j - 1][i];
			}
		}
	}
	for (int i1 = 1; i1 <= n; ++i1)
	{
		for (int i2 = 1; i2 <= n; ++i2)
		{
			for (int j1 = i1+1; j1 <= n; ++j1)
			{
				for (int j2 = i2+1; j2 <= n; ++j2)
				{
					
					if (l[i1][j2]-l[i1][i2-1]+l[j1][j2]-l[j1][i2-1]+c[j1][i2]-c[i1-1][i2]+c[j1][j2]-c[i1-1][j2]-a[i1][i2]-a[j1][j2]-a[i1][j2]-a[j1][i2]>minim)
					{
						minim = l[i1][j2] - l[i1][i2 - 1] + l[j1][j2] - l[j1][i2 - 1] + c[j1][i2] - c[i1 - 1][i2] + c[j1][j2] - c[i1 - 1][j2] - a[i1][i2] - a[j1][j2] - a[i1][j2] - a[j1][i2];
					}
				}
			}
		}
	}
	printf("%d", minim);
	scanf("%d", &minim);
	return 0;
}