# include <fstream>
using namespace std;
int v[1000003], n, t, ct;
# define INFINIT 1000000000

int main ()
{
	ifstream fin ("gardieni.in");
	ofstream fout ("gardieni.out");
	fin>>n>>t;
	for (int i=1;i<=t;i++)
		v[i]=INFINIT;
	int x, y, c;
	for (;n;--n)
	{
		fin>>x>>y>>c;
		for (int j=x;j<=y;j++)
			if (c<v[j])
				v[j]=c;
	}
	for (int i=1;i<=t;i++)
		ct+=v[i];
	fout<<ct;
	return 0;
}