#include <bits/stdc++.h>
#include <atcoder/segtree>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

ll op(ll a,ll b){
    return max(a,b);
}
ll e(){
    return 0;
}

int main(){
    int n,t;
    cin >> n >> t;
    const int m=4e5+1;
    vector<vector<int>>l(m),r(m);
    rep(i,n){
        int L,R,p;
        cin >> L >> R >> p;
        l[L].push_back(p);
        r[R].push_back(p);
    }
    multiset<ll>s;
    atcoder::segtree<ll,op,e>seg(m);
    rep(i,m){
        for(int j:l[i])s.insert(j);
        if(i!=0)for(int j:r[i-1])s.erase(s.find(j));
        if(s.size()==0)continue;
        seg.set(i,seg.prod(0,max(i-t+1,0))+*s.rbegin());
    }
    cout << seg.all_prod() << endl;
    return 0;
}