#include<iostream>
#include<iomanip>
#include<algorithm>
#include<array>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<numeric>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<unordered_map>
#include<queue>
#include<vector>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define ALL(a) (a).begin(),(a).end()
#define DUMP(o) {cerr<<#o<<" "<<o<<endl;}
#define DUMPC(o) {cerr<<#o; for(auto &e:(o))cerr<<" "<<e;cerr<<endl;}
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
const int MOD = 1e9 + 7;

signed main() {
	int n; cin >> n;
	int a[110][110] = {};
	int dp[110][110] = {};
	n++;
	FOR(i, 1, n)FOR(j, 1, n) {
		cin >> a[i][j]; dp[i][j] = a[i][j];
	}
	FOR(i, 1, n)FOR(j, 1, n)
		dp[i][j] += dp[i - 1][j] + dp[i][j - 1] - dp[i - 1][j - 1];
	int ans = -INF;
	REP(i, n - 1)REP(j, n - 1)FOR(k, i + 1, n)FOR(l, j + 1, n)
		ans = max(ans, dp[k][l] - dp[k][j] - dp[i][l] + dp[i][j]);
	cout << ans << endl;
	return 0;
}