C

//package DynamicProgramming;

import java.io.IOException;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws IOException {
        Scanner s = new Scanner(System.in);
        String m = "";
        int n = s.nextInt();
        int[][] arr = new int[n][n];
        int maxNum = 0;
        for(int i=0;i<n;i++){
           for(int j=0;j<n;j++){ 
               arr[i][j]=s.nextInt();
           }
        }
        
        int ans=Integer.MIN_VALUE;        
        for(int i=0;i<n;i++){
            int [] sum = new int[n];
            for(int j=i;j<n;j++){
                int max=Integer.MIN_VALUE;
                int tmp=0;
                for(int l=0;l<n;l++){
                    sum[l]+=arr[j][l];
                    tmp+=sum[l];
                    max=Math.max(max, tmp);
                    if(tmp<0)
                        tmp=0;
                }
                ans=Math.max(max, ans);
            }
        }
        System.out.println(ans);
    }
}