#include<iostream>
using namespace std;
int map[5009][5009]={0},n,m,x,y,ans;
int main()
{
	cin>>n>>m;
	for (int i=1;i<=n;i++)
	{
		cin>>x>>y;
		cin>>map[1+x][1+y];
	}
	for (int i=2;i<=5001;i++)
	{
		for (int j=2;j<=5001;j++)
		{
			map[i][j]+=map[i-1][j]+map[i][j-1]-map[i-1][j-1];
		}
	}
	for (int i=m;i<=5001;i++)
	{
		for (int j=m;j<=5001;j++)
		{
			int num=map[i][j]-map[i-m][j]-map[i][j-m]+map[i-m][j-m];
			if (num>ans)
			{
				ans=num;
			}
		}
	}
	cout<<ans;
	return 0;
}