#include <stdio.h>
#include <vector>
#include <bitset>
using namespace std;
#define maxn 1005
vector <int> tri[maxn];//tine triunghiul initial
int linia[2][maxn][maxn];
bitset <maxn> calculat[maxn][maxn];

int n,k;

int suma1(int foaia, int l2,int l3){//foile sunt num incepand cu 1
    //latura 1
    int i;
    int s=0;
    int li=foaia,ls=n-l2;
    for(i=li;i<=ls;i++){
        s+=tri[i][foaia-1];
    }
    return s;
}

int suma2(int foaia,int l1, int l3){
    int i;
    int s=0;
    int li=l1,ls=n-l3-foaia+1;
    for(i=li;i<ls;i++){
        s+=tri[n-foaia+1][i];
    }
    return s;
    
}

int suma3(int foaia, int l1, int l2){
    int i;
    int s=0;
    int li=l1+foaia,ls=n-l2;
    for(i=li;i<=ls;i++){
        s+=tri[i][i-foaia];
    }
    return s;    
}

int main(){
  FILE *fin=fopen("ferma2.in","r");
  FILE *fout=fopen("ferma2.out","w");
  fscanf(fin,"%d%d",&n,&k);
  int a;
  int i,j;
  for(i=1;i<=n;i++){
    for(j=0;j<i;j++){
      fscanf(fin,"%d",&a);
      tri[i].push_back(a);
    }
  }  
  //descompun k in suma de trei numere
  int l1,l2,l3;
  int maximulm=-1;
  for(l1=0;l1<=k;l1++)
    for(l2=0;l2<=(k-l1);l2++){
      l3=k-l1-l2;
      //printf("(%d,%d,%d), ",l1,l2,l3);
      a=0;
      //iau l1 laturi 1....
      for(i=1;i<=l1;i++)a+=suma1(i,0,0);
      //iau l2 laturi 2...  
      for(i=1;i<=l2;i++)a+=suma2(i,l1,0);
      //iau l3 laturi 3...  
      for(i=1;i<=l3;i++)a+=suma3(i,l1,l2);

      if(a>maximulm)maximulm=a;
    }
       //printf("\n");

  fprintf(fout,"%d\n",maximulm);
  /*printf("suma1(%d,%d,%d)=%d\n",1,0,0,suma1(1,0,0));
  printf("suma3(%d,%d,%d)=%d\n",1,1,0,suma3(1,1,0));
  printf("suma3(%d,%d,%d)=%d\n",2,1,0,suma3(2,1,0));
*/
  return 0;
}