#include<stdio.h>
int min[1000000];
int main () {
	int i,j,n,t,s=0,a,b,c;
	freopen("gardieni.in","r",stdin);
	freopen("gardieni.out","w",stdout);
	scanf("%d%d",&n,&t);
	for(i=0;i<t;++i)
		min[i]=10000000;
	for(i=0;i<n;++i){
		scanf("%d%d%d",&a,&b,&c);
		for(j=a-1;j<b;++j)
			if(c<min[j])
				min[j]=c;
	}
	for(i=0;i<t;++i)
		s+=min[i];
	printf("%d\n",s);
	return 0;
}