#include<stdio.h>
int min[1001000];
int main(){
	freopen("gardieni.in","r",stdin);
	freopen("gardieni.out","w",stdout);
	int n,t,a,b,c,i,j;
	scanf("%d%d",&n,&t);
	for(i=0;i<n;++i){
		scanf("%d%d%d",&a,&b,&c);
		for(j=a;j<=b;++j){
			if(min[j]==0)
				min[j]=c;
			else{
				if(min[j]>c)
					min[j]=c;
			}
		}
	}
	a=0;
	for(i=1;i<=t;++i)
		a+=min[i];
	
	printf("%d\n",a);
	fclose(stdin);
	fclose(stdout);
	return 0;
}