#include <bits/stdc++.h>
#include <vector>
#include <unordered_map>
using namespace std;
class node{
public:
	int start;
	int finish;
	int cost;
	//node* next;
	node(int x,int y,int z){
		start=x;
		finish=y;
		cost=z;
		//next=NULL;
	}
	node(){
		start=0;
		finish=0;
		cost=0;
		//next=NULL;
	}
};
bool my(node i,node j){
	return (i.start>j.start); 
}
int main() {
    int n,m;
    cin >>n>>m;
    vector<node> vec(n);
	unordered_map<int,vector<node> > hash;
	int flag=0;
	for(int i=0;i<n;i++){
		
		cin>>vec[i].start>>vec[i].finish>>vec[i].cost;
	}
	sort(vec.begin(),vec.end(),my);
	int ans=-1;
	for(int i=0;i<n;i++){
		int tstart=vec[i].start;
		int tfinish = vec[i].finish;
		int tcost = vec[i].cost;
		if ( hash.find(tfinish-tstart+1) == hash.end() ){
			vector<node> vn;
			vn.push_back( node(tstart,tfinish,tcost) );
			hash[tfinish-tstart+1] = vn;
		}
		else{
			vector<node> vn = hash[tfinish-tstart+1];
			int j=0;
			vn.insert(vn.begin()+j,node(tstart,tfinish,tcost));
			vn[0].cost = min(vn[0].cost,vn[1].cost);
			hash[tfinish-tstart+1] = vn;
		}
	}
	for(int i=0;i<n;i++){
		int tstart=vec[i].start;
		int tfinish = vec[i].finish;
		int tcost = vec[i].cost;
		if ( hash.find(m-(tfinish-tstart+1)) != hash.end() ) {
			vector<node> vn = hash[m-(tfinish-tstart+1)];
			int low =0;
			int high = vn.size()-1;
			int mid;
			while(low<=high){
				mid = (low + high)/2;
				if(vn[mid].start>tfinish){
					if(ans==-1){
						ans=tcost+vn[mid].cost;
					}
					else{
						ans=min(ans,tcost+vn[mid].cost);
					}					
					high=mid-1;
				}
				else{
					low=mid+1;
				}
			}
		}
	}
	cout<<ans<<endl;
}