#include<fstream>
using namespace std;

int i,j,t,n,m,lin[1001][1001],col[1001][1001],diag[1001][1001],x,k;
int rez=0,min1=10000000,c1,c2,l1,l2,d1,d2,sum,r;
int maxx(int x,int y,int z)
{
	int m1=0;
	if(x<y)
		m1=y;
	else
		m1=x;
	if(m1<z)
		m1=z;
	return z;
}
int main()
{
	FILE *f=fopen("ferma2.in","r");
	FILE *g=fopen("ferma2.out","w");
	fscanf(f,"%d%d",&n,&k);
	lin[1][0]=col[0][1]=diag[0][0]=0;
	for(i=1;i<=n;i++)
	{
		lin[i][0]=col[0][i]=diag[i-1][0]=0;
		for(j=1;j<=i;j++)
		{
			fscanf(f,"%d",&x);
			lin[i][j]+=lin[i][j-1]+x;
			col[i][j]+=col[i-1][j]+x;
			diag[i][j]+=diag[i-1][j-1]+x;
			sum+=x;
		}
	}
	m=n-k;
	for(i=n;i>1;i--)
	{
		for(j=i;j>1;j--)
		{
			rez=0;
			r=m;
			for(t=j;t>j-m;t--)
				rez+=(diag[i][t]-diag[i-r][t-r]),r--;
			if(min1>rez)
				min1=rez;
		}
	}
	fprintf(g,"%d ",sum-min1);
	/*c1=n;
	c2=1;
	l1=l2=d1=d2=n;
	for(i=1;i<=k;i++)
	{
		max1=maxx(col[c1][c2],lin[l1][l2],diag[d1][d2]);
		if(max1==col[c1][c2])
			c2++;
		else
			if(max1==lin[l1][l2])
				--l1,--l2,--c1;
			else
				--d2,--l2;
		fprintf(g,"%d ",max1);
	}*/
	return 0;
}