#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
int n,m,f[52][52][502],num,anss;
int ans,a[52][52],b[52][52],sum[52][52];
int main()
{  freopen("brike.in","r",stdin);
   freopen("brike.out","w",stdout);
   scanf("%d%d",&n,&m);
   for(int i=1;i<=n;++i)
   	 for(int j=1;j<=n-i+1;++j)
   	   scanf("%d",&a[i][j]);
   for(int i=n;i>=1;--i)
    {
    	for(int j=1;j<=i;++j)
    	{
    		b[i][j]=a[j][i-j+1];
    		sum[i][j]=sum[i][j-1]+b[i][j];
       	}
    }
    memset(f,-0x3f,sizeof(f));
    f[0][0][0]=0;
      for(int i=1;i<=n;++i)
	   {
	   	  for(int j=0;j<=i;++j)
			{
				for(int k=j;k<=m;++k)
	    	      for(int h=(j-1<0)?0:j-1;h<=i-1;++h)
	    		     f[i][j][k]=max(f[i][j][k],f[i-1][h][k-j]+sum[i][j]);
				anss=max(anss,f[i][j][m]);
			}
	   }
    printf("%d",anss);
}