#include <queue>

 #include <cstdio>

 #include <cctype>

 #include <cstring>

 #include <iostream>

 #include <algorithm>

 using namespace std;

 const int maxn =  + ;

 int n, m, r, head[maxn], dis[maxn], in_deg[maxn], edge_num, ans;

 struct Segment {

   int lef, rig, enr;

   inline bool operator < (const Segment &x) const{ return this->rig < x.rig; }

 } seg[maxn];

 struct Edge { int v, nxt; } edge[maxn * maxn];

 inline int read() {

   register char ch = ; register int w = , x = ;

   while( !isdigit(ch) ) w |= (ch == '-'),ch = getchar();

   while( isdigit(ch) ) x = (x * ) + (ch ^ ), ch = getchar();

   return w ? -x : x;

 }

 inline void Add_edge(int u, int v) {

   edge[++edge_num].v = v;

   edge[edge_num].nxt  = head[u], head[u] = edge_num;

 }

 inline void Breath_fs() {

   queue<int> q;

   for(int i = ; i <= m; ++i) dis[i] = seg[i].enr;

   for(int i = ; i <= m; ++i) if( !in_deg[i] ) q.push(i);

   while( !q.empty() ) {

     int x = q.front(); q.pop();

     for(int i = head[x]; i; i = edge[i].nxt) {

       if( dis[edge[i].v] < dis[x] + seg[edge[i].v].enr )

         dis[edge[i].v] = dis[x] + seg[edge[i].v].enr;

       if( --in_deg[edge[i].v] ==  ) q.push(edge[i].v);

     }

   }

 }

 int main(int argc, char const *argv[])

 {

   freopen("nanjolno.in", "r", stdin);

   freopen("nanjolno.out", "w", stdout);

   scanf("%d%d%d", &n, &m, &r);

   for(int i = ; i <= m; ++i)

     seg[i].lef = read(), seg[i].rig = read() + r, seg[i].enr = read();

   sort(seg + , seg + m + ), ans = ;

   for(int i = ; i <= m; ++i) for(int j = i + ; j <= m; ++j)

       if( seg[i].rig <= seg[j].lef ) Add_edge(i, j), ++in_deg[j];

   Breath_fs();

   for(int i = ; i <= m; ++i) ans = max(ans, dis[i]);

   printf("%d\n", ans);

   fclose(stdin), fclose(stdout);

   return ;

 }