#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

template <class S>
struct value_compression : vector<S> {
  bool built = false;
  using VS = vector<S>;
  using VS::VS;
  value_compression(vector<S> v) : vector<S>(move(v)) {}
  void build() {
    sort(this->begin(), this->end());
    this->erase(unique(this->begin(), this->end()), this->end());
    built = true;
  }
  template <class T>
  void convert(T first, T last) {
    assert(built);
    for (; first != last; ++first) *first = (*this)(*first);
  }
  int operator()(S x) {
    assert(built);
    return lower_bound(this->begin(), this->end(), x) - this->begin();
  }
  void clear() {
    this->clear();
    built = false;
  }
};

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, a;
  cin >> n >> a;
  a *= 2;
  vector<tuple<ll, ll, int>> evs;
  value_compression<ll> vc;
  rep(_, n) {
    ll x, y, v;
    cin >> x >> y >> v;
    x *= 2, y *= 2;
    evs.emplace_back(x-a, y, v);
    evs.emplace_back(x+1, y, -v);
    vc.emplace_back(y-a);
    vc.emplace_back(y+1);
  }
  vc.build();
  constexpr long long INF = 1002003004005006007;
  lazy_segtree<ll, [](ll x, ll y) { return max(x, y); }, []() { return -INF; }, ll, [](ll f, ll x) { return f + x; }, [](ll f, ll g) { return f + g; }, []() { return 0; }> seg(VL(vc.size(), 0));
  sort(all(evs));
  ll ans = 0;
  int xpre = -2001001001;
  for (auto [x, y, v] : evs) {
    if (x != xpre) chmax(ans, seg.all_prod());
    xpre = x;
    seg.apply(vc(y-a), vc(y+1), v);
  }
  cout << ans << '\n';
}