#include <iostream>
#include <fstream>
#define NMAX 105
using namespace std;

int n,a[NMAX][NMAX],s,smax=-500,temp[NMAX];
ifstream in("joctv.in");
ofstream out("joctv.out");

int din(int d[])
{
    int mx=-500,ma;
    ma = mx = d[1];

    for(int i=2;i<=n;i++)
    {
        if(ma>=0)
            ma = ma+d[i];
        else
            ma = d[i];
        if(mx<ma) mx = ma;

    }

    return mx;
}

int main()
{
    in >> n;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            in >> a[i][j];

    for(int i=1;i<=n;i++)
    {
        for(int k=1;k<=n;k++)
            temp[k]=0;

        for(int j=i;j<=n;j++)
        {
            for(int k=1;k<=n;k++)
                temp[k] += a[j][k];

            s = din(temp);

            if(s>smax)
                smax = s;
        }

    }

        out << smax;
    return 0;
}