#include <iostream>
#include <fstream>
#include <climits>
using namespace std;

int main()
{
 ifstream f("gardieni.in");
 ofstream g("gardieni.out");
 int N,t,i,j,jj,suma=0,min;
 long long int T;
 struct segment{int a,b,c;}S[50006];
 f>>N>>T;
 for(i=1;i<=N;i++)f>>S[i].a>>S[i].b>>S[i].c;
 for(i=1;i<=T;i++)
 {
     min=INT_MAX;
     for(j=1;j<=N;j++)
        if(S[j].a<=i&&S[j].b>=i)
            if(S[j].c<min){min=S[j].c;jj=j;
     }
suma=suma+S[jj].c;
 }
g<<suma;
return 0;
}