using namespace std;
#include <fstream>

int T, v[1000001];

int main(){
	ifstream fin("gardieni.in");
	int n,a,b,c;
	fin>>n>>T;
	c=1<<30;
	for(int i=1;i<=T;++i)
		v[i]=c;
	for( ; n ; --n){
		fin>>a>>b>>c;
		for(int i=a;i<=b;++i)
			if(v[i]>c)
				v[i]=c;
	}
	long long int s=0;
	for(int i=1;i<=T;i++)
		s+=(long long)v[i];
	ofstream fout("gardieni.out");
	fout<<s;
	return 0;
}