#include <stdio.h>

#define minim(a, b) ((a < b) ? a : b)
#define INF 2000000001
#define TMax 1000005

int N, T, C[TMax], bst;

int main(void)
{
    int i, j, a, b, c;
    
    freopen("gardieni.in", "r", stdin);
    freopen("gardieni.out", "w", stdout);

    scanf("%d %d", &N, &T);

    for (i = 1; i <= T; i++)
        C[i] = INF;
    for (i = 1; i <= N; i++)
    {
        scanf("%d %d %d", &a, &b, &c);
        for (j = a; j <= b; j++)
            C[j] = minim(C[j], c);
    }
    for (i = 1; i <= T; i++)
        bst += C[i];

    printf("%d\n", bst);
    
    return 0;
}