#include<cstdio>
#include<iostream>
#include<algorithm>
#define mysister
#define maxn 1000000
#define maxm 1000
using namespace std;
int n,m,rt,ans=0,f[maxm];
struct jinai
{
	int l,r,w;
	bool operator < (const jinai &b)const
	{
		return l<b.l;
	}
}a[maxm];
int main()
{
	freopen("milkprod.in","r",stdin);
	freopen("milkprod.out","w",stdout);
	scanf("%d%d%d",&n,&m,&rt);
	n+=rt;
	for(int i=0;i<m;i++)
	{
	  scanf("%d%d%d",&a[i].l,&a[i].r,&a[i].w);
	  a[i].r+=rt;
	}
	sort(a,a+m);
	int ans=0;
    for(int i=0;i<m;i++)
    {
      f[i]=a[i].w;
      for(int j=0;j<i;j++)
        if(a[i].l>=a[j].r)
          f[i]=max(f[i],f[j]+a[i].w);
      ans=max(ans,f[i]);
    }
    printf("%d",ans);
	return 0;
}