#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
using namespace std;
int dp[5050][5050];
int n, r;
int main()
{
    scanf("%d%d", &n, &r);
    memset(dp, 0, sizeof(dp));
    while (n--)//数据读入
    {
        int x, y, v;
        scanf("%d%d%d", &x, &y, &v);
        dp[x + 1][y + 1] = v;
    }
    for (int i = 1; i < 5002; ++i)
        for (int j = 1; j < 5002; ++j)
            dp[i][j] = dp[i][j] + dp[i][j - 1] + dp[i - 1][j] - dp[i - 1][j - 1];//二维前缀和预处理
    int ans = 0;
    for (int i = r; i < 5002; ++i)
        for (int j = r; j < 5002; ++j)
        {
            int p = dp[i][j] - dp[i][j - r] - dp[i - r][j] + dp[i - r][j - r];//递推
            ans = max(p, ans);
        }
    printf("%d\n", ans);
    return 0;
}