#include<stdio.h>
int n, t, i, j, x, y, cst, d[1000005], rezultat;
int main()
{
	freopen("gardieni.in", "rt", stdin);
	freopen("gardieni.out", "wt", stdout);
	
	scanf("%d%d", &n, &t);
	for (i = 1; i <= n; i ++){
		scanf("%d%d%d", &x, &y, &cst);
		
		for (j = x; j <= y; j ++)
			if (cst < d[j] || !d[j])
				d[j] = cst;
	}
	
	for (i = 1; i <= t; i ++)
		rezultat += d[i];
	
	printf("%d\n", rezultat);
	
	return 0;
}