#include <cstdio>

using namespace std;

int v[55][55],a[55][55];

int abs(int n){
    if(n<0){
        return -n;
    }
    return n;
}

int main(){
    int n,rasp=-105,pat,lat,sum;
    
    scanf("%d",&n);
    
    for(register int i=1;i<=n;++i){
        for(register int j=1;j<=n;++j){
            scanf("%d",&v[i][j]);
            a[i][j]=v[i][j];
            if(a[i][j]>rasp){
                rasp=a[i][j];
            }
            v[i][j]=v[i][j]+v[i-1][j];
        }
    }
    
    for(register int i1=1;i1<=n;++i1){
        for(register int i2=i1;i2<=n;++i2){
            pat=n-(i2-i1+1)+1;
            lat=i2-i1-1;
            if(lat>-1){
            for(register int k=1;k<=pat;++k){
                sum=(v[i2][k]-abs(v[i1-1][k]))+(v[i2][k+lat+1]-abs(v[i1-1][k+lat+1]));
                for(register int j=1;j<=lat;++j){
                    sum=sum+(a[i1][k+j]+a[i2][k+j]);
                }
                if(sum>rasp){
                    rasp=sum;
                }
            }
            }
        }
    }
    
    printf("%d\n",rasp);
    
    return 0;
}