#include<stdio.h>

int sc[52][52],sl[52][52],v[52][52];

int main()
{
    //freopen("date.in","r",stdin);
    int n,i,j,k,l,sol=-2000000000,s;

    scanf("%d",&n);
    for(i=1;i<=n;++i)
        for(j=1;j<=n;++j)
        {
            scanf("%d",&v[i][j]);
            sl[i][j]=sl[i][j-1]+v[i][j];
            sc[i][j]=sc[i-1][j]+v[i][j];
        }


    for(i=1;i<=n;++i)
        for(j=1;j<=n;++j)
            for(k=i,l=j;k<=n&&l<=n;++k,++l)
                {
                    s=0;

                    s+=sl[k][l]-sl[k][j-1];
                    if(i!=k)
                        s+=sl[i][l]-sl[i][j-1];

                    if(i!=k)
                    {
                        s+=sc[k-1][l]-sc[i][l];
                        if(j!=l)
                            s+=sc[k-1][j]-sc[i][j];
                    }

                    /*if(i==k)
                        s-=sl[i][l]-sl[i][j-1];
                    if(j==l)
                        s-=sc[k][l]-sc[i-1][l];
                    */

                    if(s>sol)
                        sol=s;
                }

    printf("%d\n",sol);


    return 0;
}