#include <iostream>
using namespace std;
const int N = 5010;
int s[N][N];
int main(){
    int n, r;   cin >> n >> r;
    r = min(5001, r);
    while(n -- ){
        int x, y, v;   cin >> x >> y >> v;
        x ++ , y ++ ;
        s[x][y] += v;
    }
    for(int i = 1; i <= 5001; i ++ ){
        for(int j = 1; j <= 5001; j ++ ){
            s[i][j] += s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1];
        }
    }
    int res = 0;
    for(int i = r; i <= 5001; i ++ ){
        for(int j = r; j <= 5001; j ++ ){
            res = max(res, s[i][j] - s[i - r][j] - s[i][j - r] + s[i - r][j - r]);
        }
    }
    cout << res << endl;
    return 0;
}