#include <iostream>

using namespace std;

int a[101][101];

int maxsum(int a[],int n)

{

int sum=-10000000,b=0;

int i;

for(i=0;i<n;i++)

{

if (b>0)

b+=a[i];

else

b=a[i];

if(b>sum)

sum=b;

}

return sum;

}

int maxsum2(int m,int n)

{

int sum = -10000000;

int i,j,k,max;

int* b = new int[n+1];

for (i=0;i<m;i++)

{

for(k=0;k<n;k++)

b[k]=a[i][k];

max = maxsum(b,n);

if(max>sum)

sum=max;

for(j=i+1;j<m;j++)

{

for (k=0;k<=n;k++)b[k]+=a[j][k];

max = maxsum(b,n);

if(max>sum)sum=max;

}

}

delete []b;

return sum;

}

int main()

{

int n,i,j;

cin >> n;

for (i=0;i<n;i++)

for (j=0;j<n;j++)

cin >> a[i][j];

cout << maxsum2(n,n) << endl;

return 0;

}