#include<fstream>

using namespace std;

ifstream fin("gardieni.in");
ofstream fout("gardieni.out");
int t, n, a, b, c,  m, i;
long long s;
int minim[1000005];
int main()
{
	fin>>n>>t;
	
	for(i=1; i<=t; i++)
		minim[i]=100000;
	while(n)
	{
		fin>>a>>b>>c;
		for(i=a; i<=b; i++)
			if(minim[i]>c)
					minim[i]=c;
		n--;
	}
	for(i=1; i<=t; i++)
		s+=(long long)minim[i];
	fout<<s;

	
	fin.close();
	fout.close();
	return 0;
}