#include <fstream>

using namespace std;

const char InFile[]="gardieni.in";
const char OutFile[]="gardieni.out";
const int MaxT=1000111;
const int INF=1<<30;

ifstream fin(InFile);
ofstream fout(OutFile);

int N,T,sol,vmin[MaxT],a,b,c;

int main()
{
	fin>>N>>T;
	for(register int i=1;i<=T;++i)
	{
		vmin[i]=INF;
	}
	for(register int i=1;i<=N;++i)
	{
		fin>>a>>b>>c;
		for(register int j=a;j<=b;++j)
		{
			if(vmin[j]>c)
			{
				vmin[j]=c;
			}
		}
	}
	fin.close();
	
	for(register int i=1;i<=T;++i)
	{
		sol+=vmin[i];
	}
	
	fout<<sol;
	fout.close();
	return 0;
}