#include <stdio.h>
#include<limits.h>
FILE *f=fopen("gardieni.in","r"),*g=fopen("gardieni.out","w");
long int n,t,v[1000001];

void citire(){
long int a,b,c,i,j;
long long s=0;
    fscanf(f,"%ld %ld\n",&n,&t);
    for(i=1; i<=t; i++){
        v[i]=LONG_MAX;
    }
    for(i=1; i<=n; i++){
        fscanf(f,"%ld %ld %ld\n",&a,&b,&c);
        for(j=a; j<=b; j++){
            if(c<v[j]){v[j]=c;}
        }
    }
    for(i=1; i<=t; i++){
        s=s+v[i];
    }
    fprintf(g,"%lld",s);
}


int main()
{
   citire();
    return 0;
}