#include<stdio.h>
#include<string.h>
long n,t,i,a,b,c,j,ti[1000500];
long long s;
int main()
{
 freopen("gardieni.in","r",stdin);
 freopen("gardieni.out","w",stdout);
 scanf("%ld%ld",&n,&t);
 for(i=1;i<=t;++i)
    ti[i]=2000000000;
 for(i=1;i<=n;++i)
    {scanf("%ld%ld%ld",&a,&b,&c);
     for(j=a;j<=b;++j)
        if(ti[j]>c)ti[j]=c;}
 for(i=1;i<=t;++i)s+=ti[i];
 printf("%lld\n",s);
 return 0;
}