#include <bits/stdc++.h>

using namespace std;

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

int n, m;

int sol[100001];

int main()
{
    in >> n >> m;
    for(int i = 1; i <= m; i++)
        sol[i] = INT_MAX;
    for(int i = 1; i <= n; i++)
    {
        int a, b, c;
        in >> a >> b >> c;
        for(int j = a; j <= b; j++)
            sol[j] = min(sol[j], c);
    }
    int rasp = 0;
    for(int i = 1; i <= m; i++)
        rasp += sol[i];
    out << rasp;
    return 0;
}