#include <bits/stdc++.h>
using namespace std;

const int maxn = 5010;

int a[maxn][maxn];

int main(void) {
    int n=2, r=1;
    cin>>n>>r;

    int x, y, c, maxX=r, maxY=r;
    for(int i = 1; i <= n; i++) {
        cin>>x>>y>>c;
        a[++x][++y] += c;
        maxX = max(maxX, x);
        maxY = max(maxY, y);
    }

    for(int i = 1; i <= maxX; i++){
        for(int j = 1; j <= maxY; j++){
            a[i][j] = a[i - 1][j] + a[i][j - 1] - a[i - 1][j - 1] + a[i][j];
        }
    }
    int ans = -2147483647;
    for(int i = r; i <= maxX; i++){
        for(int j = r; j <= maxY; j++){
            ans = max(ans, a[i][j] - a[i - r][j] - a[i][j - r] + a[i - r][j - r]);
        }
    }
    cout<<ans;

    return 0;
}