#include <cstdio>
#include <algorithm>
using namespace std;

const int NMAX = 1000010, INF = 0x3f3f3f3f;

int N, T, A, B, C, Min[NMAX];

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

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

    for(int i = 1; i <= T; ++ i) Min[i] = INF;

    for(int i = 1; i <= N; ++ i)
    {
        scanf("%i %i %i", &A, &B, &C);
        for(int j = A; j <= B; ++ j)
            Min[j] = min(Min[j], C);
    }

    long long Ans = 0;
    for(int i = 1; i <= T; ++ i) Ans += Min[i];
    printf("%lld\n", Ans);
}