#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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