#include <iostream>
#include <fstream>

using namespace std;

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

const int NMax = 1000005;
const int INF = 1e9;

int v[NMax];

int main()
{
    int n, t, a, b, c;
    fin >> n >> t;
    for(int i = 1; i <= t; i++){
        v[i] = INF;
    }
    for(int i = 1; i <= n; i++){
        fin >> a >> b >> c;
        for(int j = a; j <= b; j++){
            v[j] = min(v[j], c);
        }
    }
    long long int sol = 0;
    for(int i = 1; i <= t; i++){
        sol += (long long int)v[i];
    }
    fout << sol;
    return 0;
}