#include <iostream>
using namespace std;
int n,r;
int cnt;
int maxx = -1;
int XMAX = -1;
int YMAX = -1;
int f[5002][5002];
int main()
{
	cin>>n>>r;
	XMAX = r;
	YMAX = r;
	for(int i=0;i<n;i++)
	{
		int x,y,w;
		cin>>x>>y>>w;
		f[x+1][y+1] += w;
		XMAX = max(XMAX,x+1);
		YMAX = max(YMAX,y+1);

	}
	for(int i=1;i<=XMAX;i++)
	{
		for(int j=1;j<=YMAX;j++)
		{
			f[i][j] += f[i-1][j] + f[i][j-1] - f[i-1][j-1];
		}
	}
	
	for(int i=r;i<=XMAX;i++)
	{
		for(int j=r;j<=YMAX;j++)
		{
			maxx=max(maxx,f[i][j]-f[i-r][j]-f[i][j-r]+f[i-r][j-r]);
		}
	}
	cout<<maxx<<endl;
	return 0;
}