#include<bits/stdc++.h>
#define mst(a,b) memset(a,b,sizeof a)
template<class T>inline void read(T &x){x=0;char c=getchar();bool f=0;for(;!isdigit(c);c=getchar())if(c=='-')f=1;for(;isdigit(c);c=getchar())x=(x<<3)+(x<<1)+c-'0';x=f?(~(x-1)):x;}
template<class T>inline void write(T x){if(x<0)return putchar('-'),write(-x),void();if(x>=10)write(x/10);putchar(x%10+'0');return;}
template<class T>inline void print(T x){write(x);putchar('\n');}
template<typename type,typename ...T>inline void read(type &x,T&...y){read(x),read(y...);}
using namespace std;
const int N=5e3,M=1e5;
int n,m;
struct node{
	int l,r,v;
	inline friend bool operator <(node _x,node _y){
		return _x.r<_y.r;
	}
}wt[N];
int dp[M];
signed main(){
	read(n,m);
	for(int i=1;i<=n;++i){
		read(wt[i].l,wt[i].r,wt[i].v);
	}
	sort(wt+1,wt+n+1);
	mst(dp,0);
	for(int i=1,j=1;i<=m;++i){
		dp[i]=dp[i-1];
		for(;j<=n&&wt[j].r<=i;++j){
			dp[wt[j].r]=max(dp[wt[j].r],dp[wt[j].l-1]+wt[j].v);
		}
	}
	print(dp[m]);
	return 0;
}