#include <cstdio>

long long s;
int T[1000010], n, t;

int main()
{
	freopen("gardieni.in","r",stdin);
	freopen("gardieni.out","w",stdout);
	scanf("%d %d",&n,&t);
	int i, j, a, b, c;
	for (i=1; i<=t; i++) T[i]=1<<25;
	for (i=1; i<=n; i++)
	{
	    scanf("%d %d %d",&a,&b,&c);
		for (j=a; j<=b; j++)
		    if (T[j]>c) T[j]=c;
    }
	s=0;
	for (i=1; i<=t; i++) s+=T[i];
	printf("%lld",s);
}