#include <bits/stdc++.h>

using namespace std;

ifstream fin ("gardieni.in");
ofstream fout ("gardieni.out");

const int TMAX = 1e6;

int n, t;

long long ans[TMAX + 5];

int main() {
    for (int i = 1; i <= TMAX; i++)
        ans[i] = INT_MAX;
    fin >> n >> t;
    for (int i = 1; i <= n; i++) {
        int a, b;
        long long c;
        fin >> a >> b >> c;
        for (int j = a; j <= b; j++)
            ans[j] = min (ans[j], c);
    }
    long long ans_final = 0;
    for (int i = 1; i <= t; i++)
        ans_final += ans[i];
    fout << ans_final << "\n";
    return 0;
}