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

ifstream cin("gardieni.in");
ofstream cout("gardieni.out");

const int INF = 1000000000;
const int MAXT = 1000000;

int best[1 + MAXT];

int main() {
    int n, t;
    cin >> n >> t;
    for (int i = 1; i <= t; i++)
        best[i] = INF;
    for (int i = 1; i <= n; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        for (int j = a; j <= b; j++)
            best[j] = min(best[j], c);
    }
    long long answer = 0;
    for (int i = 1; i <= t; i++)
        answer += best[i];
    cout << answer << "\n";
    return 0;
}