max sum

///:-)
#include <bits/stdc++.h>
#define pb push_back
#define ll long long int
#define inf 2000000000
#define infLL 9000000000000000000
#define infULL 18446744073709551615
#define Aktaruzzaman using
#define pi (2.0*acos(0.0))
#define Pramanik namespace std;
#define vsort(v)   sort(v.begin(),v.end())
#define ull unsigned long long int
#define mem(a, b) memset(a, b, sizeof a)
#define cf 100009
#define MOD 1000000007
#define pii pair<int, int>

//int dx[]={0,1,0,-1};
//int dy[]={1,0,-1,0};
//int dx[]={1,1,0,-1,-1,-1,0,1};
//int dy[]={0,1,1,1,0,-1,-1,-1};

template <class T> inline T gcd(T a,T b)
{
    if(b==0)return a;
    return gcd(b,a%b);
}
template< class T > inline T lcm(T a,T b)
{
    a=abs(a);
    b=abs(b);
    return (a/gcd(a,b))*b;
}
template <class T> inline T is_prime(T a)
{
    if(a<2|a==4)return false;
    if(a==2||a==3||a==5)return true;
    T g=(T)sqrt(a)+1;
    for(T i=2; i<=g; i++)
    {
        if(a%i==0)return false;
    }
    return false;
}
template <class T> inline T bigmod(T n,T p,T m)
{
    if(p==0)return 1;
    if(p%2)return ((n%m)*bigmod(n,p-1,m))%m;
    else
    {
        T c=bigmod(n,p/2,m);
        return ((c%m)*(c%m))%m;
    }
}

Aktaruzzaman Pramanik

ll a[102][102], sum[102];

int main()

{
//    ios_base:: sync_with_stdio(0);
//    cin.tie(NULL);
//    cout.tie(NULL);

    ll n, i, j, k, x, y, mx;

    while(scanf("%lld", &n)==1){
    mx = (-1)*infLL;
    for(i=1; i<=n; i++)
    {
        for(j=1; j<=n; j++)
        {
            cin>>a[i][j];
            mx = max(mx, a[i][j]);
        }
    }

    if(mx<0)
    {
        printf("%lld\n", mx);
        return 0;
    }
    ll ans = (-1)*infLL;
    for(i=1; i<=n; i++)
    {

        mem(sum, 0);

        for(j=i; j<=n; j++)
        {

            x = 0;

            for(k=1; k<=n; k++)
            {
                sum[k]+=a[k][j];
                x+=sum[k];
                if(x<0)x=0;
                ans=max(x, ans);

            }

        }

    }
    if(ans==0)ans = mx;
    printf("%lld\n", ans);
}
    return 0;
}