#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
int n,t,T[1000000];
struct str{int a,b,c;} A[50005];
void citire()
{
	ifstream fin ("gardieni.in");
	fin >>n>>t;
	for (int i=1;i<=n;i++)
		fin>>A[i].a>>A[i].b>>A[i].c;
	fin.close();
}
int main ()
{
	int s=0;
	ofstream fout("gardieni.out");
	citire();
	for (int i=1;i<=n;i++)
		for (int j=A[i].a;j<=A[i].b;j++)
				if (T[j]==0 || T[j]>A[i].c)
					T[j]=A[i].c;
	for (int i=1;i<=t;i++)
			s+=T[i];
	fout<<s;
	return 0;
}