#include <stdio.h>
#include <fstream>
using namespace std;

#define in "gardieni.in"
#define out "gardieni.out"
#define dim 1000001
#define infinit (1<<30)

int N, T;
int Min[dim], C[50006], S[50006], F[50006];

int main()
{
    freopen(in,"r",stdin);
    freopen(out,"w",stdout);
    
    scanf("%d%d", &N, &T);
    for ( int i = 1; i <= N; i++ )
        scanf("%d%d%d", &S[i], &F[i], &C[i]);
    
    for ( int i = 1; i <= T; i++ )
        Min[i] = infinit;
    
    for ( int i = 1; i <= N; i++ )
        for ( int j = S[i]; j <= F[i]; j++ )
            if ( C[i] < Min[j] ) Min[j] = C[i];
            
    unsigned long long Cost = 0;
    
    for ( int i = 1; i <= T; i++ )
        Cost += Min[i];
    
    printf("%llu", Cost);
}