# include <cstdio>

# include <cstring>

# include <cstdlib>

# include <iostream>

# include <vector>

# include <queue>

# include <stack>

# include <map>

# include <set>

# include <cmath>

# include <algorithm>

using namespace std;

# define lowbit(x) ((x)&(-x))

# define pi acos(-1.0)

# define eps 1e-

# define MOD

# define INF

# define mem(a,b) memset(a,b,sizeof(a))

# define FOR(i,a,n) for(int i=a; i<=n; ++i)

# define FO(i,a,n) for(int i=a; i<n; ++i)

# define bug puts("H");

# define lch p<<,l,mid

# define rch p<<|,mid+,r

# define mp make_pair

# define pb push_back

typedef pair<int,int> PII;

typedef vector<int> VI;

# pragma comment(linker, "/STACK:1024000000,1024000000")

typedef long long LL;

int Scan() {

    int x=,f=;char ch=getchar();

    while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}

    while(ch>=''&&ch<=''){x=x*+ch-'';ch=getchar();}

    return x*f;

}

void Out(int a) {

    if(a<) {putchar('-'); a=-a;}

    if(a>=) Out(a/);

    putchar(a%+'');

}

const int N=;

//Code begin...

int a[N][N], sum[N][N], dp[N*N][N][N], n;

int dfs(int x, int col, int row){

    if (x<||(col>n&&x)) return -INF;

    if (~dp[x][col][row]) return dp[x][col][row];

    if (x==) return row==?:-INF;

    int res=-INF;

    FOR(i,max(,row-),min(x,n-col)) res=max(res,dfs(x-row,col+,i)+sum[col][row]);

    return dp[x][col][row]=res;

}

int main ()

{

    int m, ans=;

    scanf("%d%d",&n,&m); mem(dp,-);

    FOR(i,,n) FOR(j,,n-i+) scanf("%d",&a[i][j]), sum[j][i]=sum[j][i-]+a[i][j];

    FOR(i,,n) ans=max(ans,dfs(m,,i));

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

    return ;

}