#include<iostream>
#include<fstream>

using namespace std;

ifstream in("gardieni.in");
ofstream out("gardieni.out");

const int INF = 1 << 30;

long long V[1000010];

inline int mn(int a, int b)
{
	if(a < b)
		return a;
	return b;
}

int main()
{
	int N, T, i, j, st, dr, cost;
	long long sol = 0;
	
	in >> N >> T;
	
	for(i = 1; i <= T; ++i)
		V[i] = INF;
	
	for(i = 1; i <= N; ++i){
		in >> st >> dr >> cost;
		
		for(j = st; j <= dr; ++j)
			V[j] = mn(V[j], cost);
	}
	
	for(i = 1; i <= T; ++i)
		sol += V[i];
	
	out << sol;
	
	return 0;
}