#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9 + 7;
const int N = 200005;
const ll INF = 0x3f3f3f3f3f3f3f3f;
#define int long long
struct Event {
    ll x;
    int y1, y2;
    ll d;
    bool operator<(Event const& o) const {
        if (x != o.x) return x < o.x;
        return d > o.d;
    }
};
struct SegTree {
    struct Node {
        ll val, tag;
    };
    int n;
    vector<Node> st;
    SegTree(int _n) : n(_n), st(4 * n + 4, {0, 0}) {}
    void gx(int u, ll v) {
        st[u].val += v;
        st[u].tag += v;
    }
    void pushdown(int u) {
        if (st[u].tag != 0) {
            gx(u << 1, st[u].tag);
            gx(u << 1 | 1, st[u].tag);
            st[u].tag = 0;
        }
    }
    void pushup(int u) {
        st[u].val = max(st[u << 1].val, st[u << 1 | 1].val);
    }
    void update(int u, int l, int r, int x, int y, ll v) {
        if (y <= l || r <= x) return;
        if (x <= l && r <= y) {
            gx(u, v);
            return;
        }
        pushdown(u);
        int mid = l + r >> 1;
        update(u << 1, l, mid, x, y, v);
        update(u << 1 | 1, mid, r, x, y, v);
        pushup(u);
    }
    ll query_max() const {
        return st[1].val;
    }
};
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n;
    ll A;
    cin >> n >> A;
    vector<ll> X(n), Y(n), V(n);
    for (int i = 0; i < n; i++) cin >> X[i] >> Y[i] >> V[i];
    vector<ll> ys;
    ys.reserve(2 * n);
    for (int i = 0; i < n; i++) {
        ys.push_back(Y[i]);
        ys.push_back(Y[i] + A);
    }
    sort(ys.begin(), ys.end());
    ys.erase(unique(ys.begin(), ys.end()), ys.end());
    auto cal = [&](ll y) {
        return lower_bound(ys.begin(), ys.end(), y) - ys.begin();
    };
    vector<Event> ev;
    ev.reserve(2 * n);
    for (int i = 0; i < n; i++) {
        ll xs = X[i] - A;
        ll xe = X[i];
        int y1 = cal(Y[i]), y2 = cal(Y[i] + A) + 1;
        ev.push_back({xs, y1, y2, V[i]});
        ev.push_back({xe, y1, y2, -V[i]});
    }
    sort(ev.begin(), ev.end());
    SegTree st((int)ys.size() + 2);
    ll ans = -INF;
    for (auto& e : ev) {
        st.update(1, 0, st.n, e.y1, e.y2, e.d);
        ans = max(ans, st.query_max());
    }
    cout << max(ans, 0LL) << "\n";
    return 0;
}