#include<stdio.h>
#define INF 1<<22;

FILE *fin=fopen("gardieni.in","r");
FILE *fout=fopen("gardieni.out","w");

int N, T, a, b;
long long c, s;
int v[1000010];

int main(){
	
	fscanf(fin,"%d %d",&N, &T);
	
	for(int i=1;i<=T;i++){
		v[i] = INF;
	}
	
	for(int i=1;i<=N;i++){
		fscanf(fin,"%d %d %lld",&a,&b,&c);
		
		for(int j = a; j <= b; j++){
			if(v[j]>c){
				v[j] = c;
			}
		}
	}
	
	for(int i = 1; i<=T; i++){
		s+=v[i];
	}
	
	fprintf(fout,"%lld",s);
	
	
	
	return 0;
}