#include <bits/stdc++.h>

#define Max(a,b) a>b?a:b

#define rep(i,j,n) for(register int i=j;i<=n;i++)

using namespace std;

typedef long long LL;

inline LL read() { LL x=; int f=; char ch=getchar();

    while(!isdigit(ch)) { if (ch=='-') f=-; ch=getchar();}

    while(isdigit(ch)) x=(x<<)+(x<<)+(ch^),ch=getchar(); return x*f;

}

int n,m;

const int N=<<;

int a[N][N];

signed main(){

    n=read();

    rep(i,,n) rep(j,,n) a[i][j]=read()+a[i-][j]+a[i][j-]-a[i-][j-];

    LL ans=;

    rep(x1,,n) rep(y1,,n) rep(x2,x1+,n) rep(y2,y1+,n) ans=Max(ans,a[x2][y2]-a[x1-][y2]-a[x2][y1-]+a[x1-][y1-]);

    cout << ans << endl ;

    return ;

}

#include <bits/stdc++.h>

using namespace std;

typedef long long LL;

inline LL read () { LL res =  ;int f () ;char ch = getchar ();

    while (!isdigit(ch)) { if (ch == '-') f = - ;ch = getchar();}

    while (isdigit(ch)) res = (res << ) + (res << ) + (ch ^ ) ,ch = getchar(); return res * f ;

}

int n,s[][],f[],ans,p,x,ma;

signed main() {

    n=read();

    for(register int i=; i<=n; i++) f[i]=-1e9;

    for(register int i=; i<=n; i++)

        for(register int j=; j<=n; j++) {

            x=read();

            maxn=Max(maxn,x);

            s[i][j]=s[i-][j]+x;

        }

    ans=-1e9;

    for(register int i=; i<=n; i++)

        for(register int j=i; j<=n; j++)

            for(register int k=; k<=n; k++) {

                p=s[j][k]-s[i-][k]; f[k]=max(p,f[k-]+p); ans=max(ans,f[k]);

            }

    cout << ans << endl ;

    return ;

}