#include<bits/stdc++.h>
//#define int unsigned short
using namespace std;
const int N = 5005;
int n,m,ex,ey,ans; 
int /*cnm[N][N],*/f[N][N];
signed main(){
	//cout << 1 << endl;
	cin >> n >> m;
	//m = m - 1;
	//if(m != 1) m = m - 1;
	for(int i = 1;i <= n;i ++ ){
		int x,y,v;
		cin >> x >> y >> v;
		x++;
		y++;
		f[x][y]+=v;
		ex = max(ex,x);
		ey = max(ey,y); 
	}
	for(int i = 1;i <= ex;i ++ ){
		for(int j = 1;j <= ey;j ++ ){
			f[i][j] = f[i][j] + f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1];
		}
	}
	for(int i = m;i <= ex;i ++ ){
		for(int j = m;j <= ey;j ++ ){
			if(f[i][j] - f[i - m][j] - f[i][j - m] + f[i - m][j - m] > ans){
				ans = f[i][j] - f[i - m][j] - f[i][j - m] + f[i - m][j - m];
				//x = i - c + 1;
				//y = j - c + 1;
			}
		}
	}
	cout << ans << endl;
	return 0;
}