10分

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <cmath>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <functional>
#include <climits>

#define quickio ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define endl "\n"

using namespace std;
typedef long long ll;

//const int N = 1e4 + 5;
const int M = 5e3 + 5;

//struct zb
//{
//	int x;
//	int y;
//	int w;
//}zb[N];

int S[M][M];

void solve()
{
	int n, m;
	cin >> n >> m;
	int x, y, w;
	int maxx = 0, maxy = 0;
	for (int i = 0; i < n; i++)
	{
		//cin >> zb[i].x >> zb[i].y >> zb[i].w;
		cin >> x >> y >> w;
		x++;
		y++;
		if (x > maxx)
			maxx = x;
		if (y > maxy)
			maxy = y;
		//S[x][y] = w;//错了！！！！！！！！！！，可能两个目标在同一位置啊，看题啊！！！！！！！！！！！！！11
		//可能存在多个目标在同一位置上的情况。
		S[x][y] += w;
	}

	int Max = 0;
	for (int i = 1; i <= maxx; i++)
	{
		for (int j = 1; j <= maxy; j++)
		{
			S[x][y] += S[x - 1][y] + S[x][y - 1] - S[x - 1][y - 1];
		}
	}

	for (int i = m/**/; i <= maxx; i++)
	{
		for (int j = m/**/; j <= maxy; j++)
		{
			int num = S[i][j] - S[i - m][j] - S[i][j - m] + S[i - m][j - m];
			if (num > Max)
				Max = num;
		}
	}

	cout << Max << endl;
}

int main()
{
	solve();
	return 0;
}