/* -*- coding: utf-8 -*-
 *
 * 3424.cc:  No.3424 Shooting Game - yukicoder
 */

#include<cstdio>
#include<vector>
#include<set>
#include<algorithm>
#include<functional>

using namespace std;

/* constant */

const int MAX_N = 200000;
const int MAX_R = 200000 + 2;

/* typedef */

using ll = long long;
using vi = vector<int>;
using msig = multiset<int,greater<int>>;

/* global variables */

vi lps[MAX_R], rps[MAX_R];
ll dp[MAX_R];

/* subroutines */

void setmax(ll &a, ll b) { if (a < b) a = b; }

/* main */

int main() {
  int n, t;
  scanf("%d%d", &n, &t);

  int maxr = 0;
  for (int i = 0; i < n; i++) {
    int l, r, p;
    scanf("%d%d%d", &l, &r, &p);
    lps[l].push_back(p);
    rps[r].push_back(p);
    maxr = max(maxr, r);
  }

  msig ps;
  fill(dp, dp + maxr + 2, -1);
  dp[0] = 0;
  for (int i = 0; i <= maxr; i++) {
    setmax(dp[i + 1], dp[i]);

    for (auto p: lps[i]) ps.insert(p);

    if (! ps.empty())
      setmax(dp[min(maxr + 1, i + t)], dp[i] + *ps.begin());
    
    for (auto p: rps[i]) ps.erase(ps.find(p));
  }

  printf("%lld\n", dp[maxr + 1]);
  
  return 0;
}