#include <iostream>
#include <fstream>
#include <climits>
using namespace std;
ifstream f("gardieni.in");
ofstream g("gardieni.out");
int main()
{
    long long int s=0, smax=INT_MAX, Smax=0, N, T, i, j;
    f>>N>>T;
    struct segment{int a, b, c;}S[50006];
    for(i=1; i<=N; i++)f>>S[i].a>>S[i].b>>S[i].c;
    for(i=1; i<=T; i++)
    {
        for(j=1; j<=N; j++)
        {
            if(S[j].a<=T && T<=S[j].b)s=S[j].c;
            if(s<smax) smax=s;
        }
    Smax+=smax;
    smax=INT_MAX;
    }
    g<<Smax;
    return 0;
}