#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> P;
typedef pair<int,pair<int,int>> PP;
typedef long long ll;

const double EPS = 1e-9;
const int INF = 1e9;
const int MOD = 1e9+7;

int dy[] = {0,1,0,-1};
int dx[] = {1,0,-1,0};

int compress(vector<int>& X){
	vector<int> x = X;
	sort(x.begin(),x.end());
	x.erase(unique(x.begin(),x.end()),x.end());
	for(int i=0;i<X.size();i++){
		X[i] = lower_bound(x.begin(),x.end(),X[i]) - x.begin();
	}
	return x.size();
}
int calc(int l, int r, int u, int d, vector<vector<int> >& sum) {
	if(l-1<0 && u-1<0)return sum[d][r];
	if(l-1<0)return sum[d][r] - sum[u-1][r];
	if(u-1<0)return sum[d][r] - sum[d][l-1];
	return sum[d][r] - sum[d][l-1] - sum[u-1][r] + sum[u-1][l-1];
}

int main(void) {
	int N,B;
	cin >> N >> B;
	vector<int> x(N),y(N),p(N);
	for(int i=0;i<N;i++){
		cin >> x[i] >> y[i] >> p[i];
	}
	//座標圧縮
	int w = compress(x),h = compress(y);

	//２次元配列に代入
	vector<vector<int>> v(h,vector<int>(w)),t(h,vector<int>(w));
	for(int i=0;i<N;i++){
		v[y[i]][x[i]] += p[i];
		t[y[i]][x[i]]++;
	}
	//累積和
	for(int i=0;i<h;i++){
		for(int j=0;j<w-1;j++){
			v[i][j+1] += v[i][j];
			t[i][j+1] += t[i][j];
		}
	}
	for(int j=0;j<w;j++){
		for(int i=0;i<h-1;i++){
			v[i+1][j] += v[i][j];
			t[i+1][j] += t[i][j];
		}
	}

	//x1~x2について全探索
	//その中でy1~y2でしゃくとり法
	int ret = 0;
	for(int x1=0;x1<w;x1++){
		for(int x2=x1;x2<w;x2++){
			int y1=0,y2=0;
			while(y2 < h){
				if(calc(x1,x2,y1,y2,v) <= B){
					ret = max(ret,calc(x1,x2,y1,y2,t));
					y2++;
				}else{
					y1++;
				}
			}
		}
	}
	cout << ret << endl;
	return 0;
}