#include <fstream>
using namespace std;

#define Nmax 1011
#define oo 1000000011

int N,K;
int A[Nmax][Nmax];
int Sum[Nmax][Nmax];
int Min=oo,Max=0;

void cit()
{
    scanf("%d%d",&N,&K);
    for (int i=1;i<=N;++i)
        for (int j=1;j<=i;++j)
            scanf("%d",&A[i][j]);
}

void make_sum()
{
    for (int i=1;i<=N;++i)
    {
        for (int j=1;j<=i;++j)
            Sum[i][j]=Sum[i][j-1]+A[i][j];
        Max+=Sum[i][i];
    }
}

int main()
{
    freopen("ferma2.in","r",stdin);
    freopen("ferma2.out","w",stdout);

    cit();
    make_sum();
    for (int i=N-K;i<=N;++i)
        for (int j=N-K;j<=i;++j)
        {
            int S=0;
            for (int i2=i,j2=j,j3=1;j3<=N-K;++j3,--j2,--i2)
                S+=Sum[i2][j2]-Sum[i2][j2-(N-K-j3+1)];
            Min=min(S,Min);
        }

    printf("%d\n",Max-Min);

    return 0;
}