#include<fstream.h>
long long int x[1000000],s,n,t,a,b,c;
ifstream in("gardieni.in");
ofstream out("gardieni.out");
int main()
{	long long int i,j;
	in>>n>>t;
	for(j=1;j<=n;j++)
	{	in>>a>>b>>c;
		for(i=a;i<=b;i++)
			if((c<x[i])||(x[i]==0))x[i]=c;
	}	
	for(i=1;i<=t;i++)
		s=s+x[i];
	out<<s;
	in.close();
	out.close();
	return 0;
}