#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

ll op(ll a, ll b){
    return max(a, b);
}
ll e(){return 0;}
using p = pair<ll, ll>;
using q = pair<ll, p>;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, T; cin >> n >> T;
    vector<q> vq;
    ll m = 0;
    rep(i, n){
        ll l, r, P; cin >> l >> r >> P;
        vq.push_back({l, {r, P}});
        m = max(m, r);
    }sort(all(vq));
    

    segtree<ll, op, e> seg(m+1);
    int itr = 0;
    set<p> st;
    multiset<ll> ms;
    rep(i, m+1){
        if(itr < n){
            while(vq[itr].first <= i){
                st.insert({vq[itr].second.first, itr});
                ms.insert(vq[itr].second.second);
                itr++;
                if(itr >= n)break;
            }
        }
        ll j = 0;
        if(ms.size()){
            j = *ms.rbegin();
        }
        if(i < T){
            seg.set(i, j);
        }else{
            seg.set(i, seg.prod(0, i-T+1) + j);
        }
        while(st.size() > 0){
            auto it = st.begin();
            ll r = it->first, k = it->second;
            if(i < r)break;
            st.erase({r, k});
            auto it2 = ms.find(vq[k].second.second);
            ms.erase(it2);
        }
    }cout << seg.all_prod() << endl;

    return 0;
}