#include<stdio.h>

#define minim(a,b) (a<b ? a : b)
#define ll long long
#define INF 1000000000

int f[1000006],n,t;
ll s;

int main ()
{
    int i,j,a,b,c;
    freopen("gardieni.in","r",stdin);
    freopen("gardieni.out","w",stdout);
    scanf("%d%d",&n,&t);
    for(i=1;i<=1000002;i++)
        f[i]=INF;
    for(i=1;i<=n;i++)
    {
        scanf("%d%d%d",&a,&b,&c);
        for(j=a;j<=b;j++)
            f[j]=minim(f[j],c);
    }
    for(i=1;i<=t;i++)
        s+=f[i];
    printf("%lld\n",s);
    return 0;
}