#include<stdio.h>
int n,t,a[50006],b[50006],c[50006],i,j;
long long e,d[1000001];
int main() {
    freopen("gardieni.in","r",stdin),freopen("gardieni.out","w",stdout),scanf("%d%d",&n,&t);
    for(i=1;i<=n;i++)
        scanf("%d%d%d",a+i,b+i,c+i);
    for(i=1;i<=t;i++)
        d[i]=1000001;
    for(i=1;i<=n;i++)
    for(j=a[i];j<=b[i];j++)
    if(c[i]<d[j])
        d[j]=c[i];
    for(i=1;i<=t;i++)
        e+=d[i];
    printf("%lld",e);
}