#include<stdio.h>
#define Tm (1<<20)
#define Inf (1<<20)
#define min(a,b) ((a)<(b)?(a):(b))
int M[Tm];

int main()
{
    int n,t,a,b,c,i;
    long long ans=0;

    freopen("gardieni.in","r",stdin);
    scanf("%d%d",&n,&t);
    
    for(i=1;i<=t;++i)
        M[i]=Inf;
        
    while(n--)
    {
        scanf("%d%d%d",&a,&b,&c);
        for(i=a;i<=b;++i)
            M[i]=min(M[i],c);
    }

    for(i=1;i<=t;++i)
        ans+=M[i];

    freopen("gardieni.out","w",stdout);
    printf("%lld\n",ans);
    return 0;
}