#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000005
#define Inf64 1000000000000000001LL
long long op(long long a,long long b){
	return max(a,b);
}
long long e(){
	return 0;
}
long long mapping(long long a,long long b){
	return a + b;
}
long long composition(long long a,long long b){
	return a + b;
}
long long id(){
	return 0;
}
int main(){
	
	long long N,A;
	cin>>N>>A;
	A *= 2;
	vector<long long> x(N),y(N),v(N);
	rep(i,N){
		cin>>x[i]>>y[i]>>v[i];
		x[i] *= 2;
		y[i] *= 2;
	}
	auto tx = x;
	rep(i,N){
		tx.push_back(x[i]+A);
		tx.push_back(x[i]+A+1);
		tx.push_back(x[i]+A-1);
	}
	sort(tx.begin(), tx.end());
	tx.erase(unique(tx.begin(), tx.end()), tx.end());
	vector<long long> ty;
	rep(i,N){
		ty.push_back(y[i]-A);
		ty.push_back(y[i]+1);
	}
	sort(ty.begin(), ty.end());
	ty.erase(unique(ty.begin(), ty.end()), ty.end());
	vector Add(tx.size(),vector<vector<long long>>());
	rep(i,N){
		int xx = lower_bound(tx.begin(), tx.end(), x[i]) - tx.begin();
		int ll = lower_bound(ty.begin(), ty.end(), y[i]-A) - ty.begin();
		int rr = lower_bound(ty.begin(), ty.end(), y[i]+1) - ty.begin();
		Add[xx].push_back({ll,rr,v[i]});
	}
	lazy_segtree<long long, op, e, long long, mapping, composition, id> seg(ty.size());
	long long ans = 0;
	int ci = 0;
	rep(i,tx.size()){
		rep(j,Add[i].size()){
			int l = Add[i][j][0];
			int r = Add[i][j][1];
			long long v = Add[i][j][2];
			seg.apply(l, r, v);
		}
		while(tx[i] - tx[ci] > A){
			rep(j,Add[ci].size()){
				int l = Add[ci][j][0];
				int r = Add[ci][j][1];
				long long v = Add[ci][j][2];
				seg.apply(l, r, -v);
			}
			ci++;
		}
		ans = max(ans, seg.all_prod());
	}
	cout<<ans<<endl;
	return 0;
}