#include <cstdio>

#include <cstring>

#include <iostream>

#include <algorithm>

using namespace std;

long long ans = ,n, m, sum[][];

long long read()

{

    long long res = , f = ;

    char ch = getchar();

    while (ch < '' || ch > '')

        if (ch == '-')

        {

            f = -;

            ch = getchar();

        }

    while (ch >= '' && ch <= '')

    {

        res = res *  + ch - '';

        ch = getchar();

    }

    return res * f;

}

int main()

{

    n = read();

    m = read();

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

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

        {

            sum[i][j] = read();

            sum[i][j] += sum[i][j - ];

        }

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

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

        {

            long long maxx = sum[i][min(n, j + m - )] - sum[i][max((long long), j - m)];

            for (int k = ; k < m; k++)

            {

                int l = max(j - m + k,(long long)), r = min(j + m -  - k,n);

                if (i + k <= n)

                    maxx += sum[i + k][r] - sum[i + k][l];

                if (i - k >= )

                    maxx += sum[i - k][r] - sum[i - k][l];

            }

            ans = max(maxx, ans);

        }

    printf("%lld\n", ans); 

    return ;

}