#include<stdio.h>

FILE*f=fopen("gardieni.in","r");
FILE*g=fopen("gardieni.out","w");

int n,T,s[1000100],i,j,a,b,c,sum;

int min ( int a, int b ) {
	
	if ( a < b )
		return a ;
	
	return b ;
	
}

int main () {
	
	fscanf ( f , "%d %d\n" , &n , &T ) ; 
	
	for ( i = 1 ; i <= T ; ++i )
		s[ i ] = 1 << 29 ;

	for ( i = 1 ; i <= n ; ++i ){
		
		fscanf ( f , "%d %d %d", &a , &b, &c ) ;
		
		for ( j = a ; j <= b ; ++j ) 
			s[ j ] = min ( s[j] , c ) ;
		
	}
	
	for ( i = 1 ; i <= T ; ++i )
		sum += s[ i ] ;
	
	fprintf ( g , "%d\n" , sum ) ;
	
	fclose(f);
	fclose(g);
	
	return 0;
	
}