#include <stdio.h>
int main()
{
    int i,j,k,p,q,r,n,t;
	int cost[1000001];
	long long sum;

	freopen("gardieni.in","r",stdin);
	freopen("gardieni.out","w",stdout);

	scanf("%d%d",&n,&t);
	for (i=1; i<=t; i++)
		cost[i]=20000000;
    for (i=1; i<=n; i++)
    {
        scanf("%d %d %d",&p,&q,&r);
        for (j=p; j<=q; j++)
            if (r<cost[j]) cost[j]=r;
    }
    sum=0;
    for (i=1; i<=t; i++)
        sum+=cost[i]; 

    printf("%lld",sum);    
    return 0;    
}