#include <iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
using namespace std;

int a[51][51],n,s=-1000000000;

int main()
{
//freopen("date.in","r",stdin);

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

for(int i1=1; i1<n; i1++)
    for(int j1=1; j1<n; j1++)
    for(int i2=i1+1; i2<=n; i2++)
    for(int j2=j1+1; j2<=n; j2++)
    {
        int ss=0;
        for(int k=j1; k<=j2; k++){ ss+=a[i1][k]; ss+=a[i2][k];  }
        for(int k=i1+1; k<i2; k++){ss+=a[k][j1]; ss+=a[k][j2]; }
        if(ss>s)s=ss;



    }

cout<<s;
    return 0;
}