#include<stdio.h>
long m[1000001],x[50010],y[50010],c[50010];
int main()
{	long i,j,n,t,cost;
	FILE *f=fopen("gardieni.in","r");
	fscanf(f,"%ld%ld",&n,&t);
	for (i=1;i<=n;i++)
		fscanf(f,"%ld%ld%ld",&x[i],&y[i],&c[i]);
	fclose(f);
	for (i=1;i<=t;i++)
		m[i]=999999999;
	for (i=1;i<=n;i++)
		for (j=x[i];j<=y[i];j++)
			if (m[j]>c[i]) m[j]=c[i];
	cost=0;
	for (i=1;i<=t;i++)
		cost+=m[i];
	FILE *g=fopen("gardieni.out","w");
	fprintf(g,"%ld\n",cost);
	fclose(g);
	return 0;
}