#include<stdio.h>
#include<string.h>
long sum[1000003],i,j,n,t,a,b,c;
long long suma;
int main()
{
    freopen("gardieni.in","r",stdin);
    freopen("gardieni.out","w",stdout);
    scanf("%ld%ld",&n,&t);
    for(i=1;i<=n;i++)
    {
                     scanf("%ld%ld%ld",&a,&b,&c);
                     for(j=a;j<=b;j++)
                                      if (sum[j]==0)
                                      {  
                                                    sum[j]=c;suma+=c;
                                      }
                                      else
                                      if (sum[j]>c)
                                      {
                                                    suma-=sum[j]-c;
                                                    sum[j]=c;
                                      }
    }
    printf("%lld\n",suma);
    return 0;
}