#include<bits/stdc++.h>
using namespace std;
int mat[101][101], pre[101][101];
int n, m;
 
// pre[i][j] -- sum from (1, 1) to (i, j)
void get_sum(){
	for(int i=1; i<=n; i++){
		for(int j=1; j<=m; j++)
			pre[i][j] = pre[i][j-1] + mat[i][j];
	}
}
 
int query(int i, int l, int r){
	return pre[i][r] - pre[i][l-1];
}
 
 
int main(){
	cin >> n; m = n;
	for(int i=1; i<=n; i++){
		for(int j=1; j<=m; j++){
			cin >> mat[i][j];
		}
	}
	get_sum();
	int mx = 1e-9;
 
	for(int l=1; l<=m; l++){
		for(int r=l; r<=m; r++){
			int curs = 0;
			for(int i=1; i<=n; i++){
				curs += query(i, l, r); // curs += arr[i]
				mx = max(mx, curs);
				if(curs < 0)
					curs = 0;
 
			}
		}
	}
	cout << mx << endl;
}
 

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NAowIC0yIC03IDAgOSAyIC02IDIKLTQgMSAtNCAxIC0xCjggMCAtMgo=

4
0 -2 -7 0 9 2 -6 2
-4 1 -4 1 -1
8 0 -2