#include<cstdio>
#define INF 2000000000
int n,t,a,b,c,i,j,x[1001000];
long long s;
FILE *f,*g;
int minim(int a,int b){
    if(a<b)
        return a;
    return b;
}
int main(){
    f=fopen("gardieni.in","r");
    g=fopen("gardieni.out","w");
    fscanf(f,"%d%d",&n,&t);
    for(i=1;i<=t;i++){
        x[i]=INF;
    }
    for(i=1;i<=n;i++){
        fscanf(f,"%d%d%d",&a,&b,&c);
        for(j=a;j<=b;j++){
            x[j]=minim(x[j],c);
        }
    }
    for(i=1;i<=t;i++){
        s+=x[i];
    }
    fprintf(g,"%lld",s);



    fclose(f);
    fclose(g);
    return 0;
}