#include <iostream>
#include<algorithm>
using namespace std;
#define N 5010
struct x
{
	int x, y, v;
};
int a[N][N];
//long long  sum[N][N];
x x1[N];
long long top;
int main()
{
	int maxx = 1, maxy = 1;
	int n, m;
	cin >> n >> m;
	for (int i = 1;i <= n;i++)
	{
		int x, y, v;
		cin >> x >> y >> v;
		a[x + 1][y + 1] = v;
		if (x + 1 > maxx)maxx = x + 1;
		if (y + 1 > maxy)maxy = y + 1;
	}
	for (int i = 1;i <= maxx;i++)
		for (int j = 1;j <= maxy;j++)
			a[i][j] += a[i - 1][j] + a[i][j - 1] - a[i - 1][j - 1];
	int  max1 = 0;
	for(int i=m;i<=maxx;i++)
		for (int j = m;j <= maxy;j++)
		{
			int sum = a[i][j] - a[i - m][j] - a[i][j - m] + a[i - m][j - m];
			max1 = max(sum, max1);
		}
	cout << max1;
}