#include<bits/stdc++.h>
using namespace std;
#define N 105
#define INF 0x3f3f3f3f
int n, a[N][N], b[N], s[N][N];//b[j]:子矩阵第j列的加和 s[i][j]:第j列的第1行到第i行的元素加和 
int mx = -INF;
int main()
{
    cin >> n;
    for(int i = 1; i <= n; ++i)
        for(int j = 1; j <= n; ++j)
        { 
            cin >> a[i][j];
            s[i][j] = s[i-1][j] + a[i][j];
        }
    for(int i1 = 1; i1 <= n; ++i1)//子矩阵第一行为原矩阵的第i1行，最后一行为原矩阵的第i2行 
        for(int i2 = i1; i2 <= n; ++i2)
        {
            for(int j = 1; j <= n; ++j)
                b[j] = s[i2][j] - s[i1-1][j];
            int sum = 0;
            for(int j = 1; j <= n; ++j)//双指针法求最大子段和
            {
                if(sum < 0)
                    sum = b[j];
                else
                    sum += b[j];
                mx = max(mx, sum);
            }
        }
    cout << mx;
    return 0;
}