import static java.lang.Math.min;

import java.util.*;
import java.io.*;

public class C implements Runnable {

	public static void main(String args[]) {
		new Thread(new C()).start();
	}

	BufferedReader br;
	StringTokenizer st;
	PrintWriter out;
	private String FNAME = "cut";
	boolean eof = false;

	@Override
	public void run() {
		try {
			Locale.setDefault(Locale.US);
			br = new BufferedReader(new FileReader(FNAME + ".in"));
			out = new PrintWriter(FNAME + ".out");
			solve();
			br.close();
			out.close();

		} catch (Exception e) {
			e.printStackTrace();
			System.exit(566);
		}
	}

	String nextToken() {
		while (st == null || !st.hasMoreTokens()) {
			try {
				st = new StringTokenizer(br.readLine());
			} catch (IOException e) {
				eof = true;
				return "0";
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(nextToken());
	}

	long nextLong() {
		return Long.parseLong(nextToken());
	}

	double nextDouble() {
		return Double.parseDouble(nextToken());
	}

	void My_Assert(boolean b, String s) {
		if (!b)
			throw new Error("Assertion " + s);
	}

	long[][] f, c;
	boolean[] was;
	int n;


	final long INF = (long) 1e12;

	private void solve() {
		n = nextInt();
		int m = nextInt();
		f = new long[n][n];
		c = new long[n][n];

		for (int i = 0; i < m; i++) {
			int a = nextInt();
			int b = nextInt();
			c[a - 1][b - 1] += nextLong();
		}

		was = new boolean[n];

		Queue<Integer> q;
		int[] p;
//		for (int it = 0; it < 2; it++) {
		while (true) {
			Arrays.fill(was, false);
			q = new LinkedList<Integer>();
			p = new int[n];
			q.add(0);
			was[0] = true;

			while (!q.isEmpty()) {
				int u = q.poll();

				for (int i = 0; i < n; i++)
					if (!was[i] && c[u][i] > f[u][i]) {
						was[i] = true;
						p[i] = u;
						q.add(i);
					}
			}
			if (!was[n - 1])
				break;



			long minc = INF;
			int t = n - 1;
			int u;
			while (t != 0) {
				u = p[t];
				minc = min(minc, c[u][t] - f[u][t]);
				t = u;
			}

//			System.err.println(minc);

			t = n - 1;
			while (t != 0) {
				f[p[t]][t] += minc;
				f[t][p[t]] -= minc;
				t = p[t];
			}
		}

		Arrays.fill(was, false);
		q = new LinkedList<Integer>();
		q.add(0);
		was[0] = true;

		while (!q.isEmpty()) {
			int u = q.poll();

			for (int i = 0; i < n; i++)
				if (!was[i] && c[u][i] > f[u][i]) {
					was[i] = true;
					q.add(i);
				}
		}

		int ans = 0;
		for (int i = 0; i < n; i++)
			if (was[i])
				ans++;

		out.println(ans);
		for (int i = 0; i < n; i++)
			if (was[i])
				out.print(i + 1 + " ");

	}

}