#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXN 1000
int a,b,n,m,p,k;
int arr[MAXN];
#define N_INF -999999
ll mat[1001][1001];
ll dp[1001][1001][3];
ll f(int i, int j, int k){
    if(i<0 || j<0 || j>=n || i>=n) return N_INF;
    if(dp[i][j][k]!=N_INF) return dp[i][j][k];
    if(i==0 && k==1){
        return dp[i][j][1] = mat[i][j];
    }
    if(j==0 && k==0){
        return dp[i][j][0] = mat[i][j];
    }
    if(j==n-1 && k==2){
        return dp[i][j][2] = mat[i][j];
    }
    ll res = N_INF;
    if(k==0){
       return dp[i][j][k] = max(mat[i][j], max(f(i, j-1, 1), f(i, j-1, 0))+mat[i][j]);
    }
    if(k==1){
        return dp[i][j][k] = max(mat[i][j], max(f(i-1, j, 0), max(f(i-1, j, 2), f(i-1, j, 1)))+mat[i][j]);
    }
    if(k==2){
        return dp[i][j][k] = max(mat[i][j], max(f(i, j+1, 2), f(i, j+1, 1))+mat[i][j]);
    }
}
int main() {
    ios_base::sync_with_stdio(false);
   // freopen("C:\\in.txt", "r", stdin);
    cin >> n;
    for(int i=0; i<n; ++i){
        for(int j=0; j<n; ++j){
           cin >> mat[i][j];
        }
    }
    for(int i=0; i<n; ++i){
        for(int j=0; j<n; ++j){
            for(int k=0; k<3; ++k){
                dp[i][j][k] = N_INF;
            }
        }
    }
    ll max_ = N_INF;
    for(int i=0; i<n; ++i){
        for(int j=0; j<n; ++j){
            for(int k=0; k<3; ++k){
                max_ = max(max_, f(i,j,k));
             }
        }
    }
    cout << max_ << endl;
    return 0;
}