#include<stdio.h>

int i,j,min[1<<20],a,b,c,n,t;
long long rez;

int main()
{
	freopen("gardieni.in","r",stdin);
	freopen("gardieni.out","w",stdout);
	
	scanf("%d %d",&n,&t);
	
	for(i=1;i<=n;++i)
	{
		scanf("%d%d%d",&a,&b,&c);
		
		for(j=a;j<=b;++j)
			if(!min[j]||min[j]>c) min[j]=c;
	}
	
	for(i=1;i<=t;++i)
		rez=rez+(long long)(min[i]);
	
	printf("%lld\n",rez);
	
	fclose(stdin);
	fclose(stdout);
	
	return 0;
}