#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

const char iname[] = "gardieni.in";
const char oname[] = "gardieni.out";

vector <int> bst;

int main(void)
{
    ifstream in(iname);
    ofstream out(oname);
    int N, T;

    in >> N >> T;
    bst.resize(T + 1, 1 << 21);
    for (int i = 0; i < N; ++ i) {
        int a, b, cst;
        in >> a >> b >> cst;
        for (int j = a; j <= b; ++ j)
            if (bst[j] > cst)   bst[j] = cst;
    }
    long long res = 0;
    for (int i = 1; i <= T; ++ i)
        res += bst[i];

    out << res;

    in.close(), out.close();
    return 0;
}