#include <bits/stdc++.h>
using namespace std;
int S[55][55],A[55][55];
int main(){
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n;++j){
            scanf("%d",&A[i][j]);
            S[i][j]=S[i-1][j]+S[i][j-1]-S[i-1][j-1]+A[i][j];
        }
    int Max=-INT_MAX;
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n;++j){
            int Sum;
            if(A[i][j]>Max) Max=A[i][j];
            int l=i+1,c=j+1;
            if(l<=n&&c<=n){
                Sum=S[i+1][j+1]+S[i-1][j-1]-S[i][j-1]-S[i-1][j];
                if(Sum>Max) Max=Sum;
            }
            ++l;++c;
            while(l<=n&&c<=n){
                int Sum1,Sum2;
                Sum1=S[l][c]+S[i-1][j-1]-S[l][j-1]-S[i-1][c];
                Sum2=S[l-1][c-1]+S[i][j]-S[l-1][j]-S[i][c-1];
                if(Sum1-Sum2>Max) Max=Sum1-Sum2;
                ++l;++c;
            }
        }
    printf("%d\n",Max);
    fclose(stdin);fclose(stdout);
    return 0;
}