// map[x+1][y+1] = w; 也能过。。。。。
import java.util.*;

public class Main{

    void run(){
        int n = jin.nextInt();
        int r = jin.nextInt();

        int row = 5000;
        int col = 5000;

        for (int i = 0 ;i < n ; i++){
            int x = jin.nextInt();
            int y = jin.nextInt();
            int w = jin.nextInt();
            map[x+1][y+1] += w;
            row = Math.max(row, x+1);
            col = Math.max(col, y+1);
        }


        int res = 0;
        for (int i = 1 ; i <= row; i++){
            for (int j = 1 ; j <= col ;j++){
                map[i][j] += map[i-1][j] + map[i][j-1] - map[i-1][j-1];
            }
        }

        for (int i = r ; i <= row  ; i++){
            for (int j = r ; j <= col; j++){
                res = Math.max(res, map[i][j] - map[i-r][j] - map[i][j-r] + map[i-r][j-r] );
            }
        }

        System.out.println(res);

    }

    int[][] map = new int[5002][5002];
    private Scanner jin = new Scanner(System.in);
    public static void main(String[] args) throws Exception {new Main().run();}
}