import java.io.*;
import java.util.*;
public class Main {
// 使用快速IO，应对 10^6 级别数据
static class FastReader {
BufferedReader br;
StringTokenizer st;
public FastReader() {
br = new BufferedReader(new InputStreamReader(System.in));
}
String next() {
while (st == null || !st.hasMoreElements()) {
try {
String line = br.readLine();
if (line == null) return null;
st = new StringTokenizer(line);
} catch (IOException e) {
e.printStackTrace();
}
}
return st.nextToken();
}
int nextInt() {
return Integer.parseInt(next());
}
}
public static void main(String[] args) {
FastReader in = new FastReader();
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
String nStr = in.next();
if (nStr == null) {
out.close();
return;
}
int n = Integer.parseInt(nStr);
int m = in.nextInt();
int k = in.nextInt();
// 使用数组模拟邻接表（链式前向星），节省内存
int[] head = new int[n + 1];
Arrays.fill(head, -1);
int[] to = new int[2 * m];
int[] next = new int[2 * m];
int edgeCount = 0;
for (int i = 0; i < m; i++) {
int u = in.nextInt();
int v = in.nextInt();
int w = in.nextInt();
// 只加入距离 <= k 的合法边
if (w <= k) {
to[edgeCount] = v;
next[edgeCount] = head[u];
head[u] = edgeCount++;
to[edgeCount] = u;
next[edgeCount] = head[v];
head[v] = edgeCount++;
}
}
List<Integer> ans = new ArrayList<>();
// 统计每个节点在合法子图中的度数
for (int i = 1; i <= n; i++) {
int degree = 0;
for (int e = head[i]; e != -1; e = next[e]) {
degree++;
}
// 度数为 0 或 1 的节点就是可能的终止位置
if (degree <= 1) {
ans.add(i);
}
}
// 输出结果
out.println(ans.size());
for (int i = 0; i < ans.size(); i++) {
out.print(ans.get(i));
if (i != ans.size() - 1) {
out.print(" ");
}
}
out.println(); // 打印换行
out.flush();
out.close();
}
}
