#include <iostream>
#include <fstream>

using namespace std;

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

long int N,T,i,j,jj,cost,mini=2097152;
struct segment{int a,b,c;}S[50005];
int main()
{
    f>>N;
    f>>T;
    for(i=1;i<=N;i++)
    {
        f>> S[i].a >> S[i].b >> S[i].c;
    }
    for(i=1;i<=T;i++)
       {
           mini=2097152;
           for(j=1;j<=N;j++)
            if(S[j].a <=i && S[j].b >=i)
                if(S[j].c<=mini)
                {
                    mini=S[j].c;
                    jj=j;
                }
                cost+=S[jj].c;
        }
    g<<cost;
    f.close();
    g.close();
    return 0;
}