#include <bits/stdc++.h>

using namespace std;

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

int n, m;

vector <int> v[500001];

int main()
{
    in >> n >> m;
    for(int i = 1; i <= n; i++)
    {
        int a, b, c;
        in >> a >> b >> c;
        for(int j = a; j <= b; j++)
        {
            v[j].push_back(c);
        }
    }
    int sum = 0;
    for(int i = 1; i <= m; i++)
    {
        int minim = 1e9;
        for(auto x:v[i])
        {
            minim = min(minim, x);
        }
        sum += minim;
    }
    out << sum;
    return 0;
}