#include<stdio.h>


int vec[1000005];
int a,b,c,n,t;
long long suma;

int main()
{

    freopen("gardieni.in","r",stdin);
    freopen("gardieni.out","w",stdout);
    scanf("%d %d",&n,&t);

    for(int i=1;i<=n;i++)
    {
    scanf("%d %d %d",&a,&b,&c);
    for(int j=a;j<=b;j++)
    if(vec[j]==0) vec[j]=c;
    else if(vec[j]>c) vec[j]=c;
    }
    for(int i=1;i<=t;i++)

      suma+=(long long)vec[i];
     printf("%lld",suma);
}