266

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

public class Solution {

    public static int[] bfs(List<Integer>[] g, int s) {
        int vertexCount = g.length;

        boolean[] used = new boolean[vertexCount];
        Arrays.fill(used, false);
        int[] p = new int[vertexCount];
        Arrays.fill(p, -1);
        int[] d = new int[vertexCount];
        Arrays.fill(d, Integer.MAX_VALUE);

        Queue<Integer> q = new LinkedList<Integer>();

        p[s] = s;
        d[s] = 0;
        used[s] = true;
        q.add(s);

        while (!q.isEmpty()) {
            int u = q.remove();
            for (int v : g[u]) {
                if (!used[v]) {
                    used[v] = true;
                    q.add(v);
                    d[v] = d[u] + 1;
                    p[v] = u;
                }
            }
        }
        return d;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new FileReader("input.txt"));
        String[] arr = in.readLine().split(" ");

        int n = Integer.parseInt(arr[0]);
        int m = Integer.parseInt(arr[1]);

        List<Pair> e = new ArrayList<Pair>();
        List<Integer>[] g = new List[n];

        for (int i = 0; i < n; i++) {
            g[i] = new ArrayList<Integer>();
        }

        for (int i = 0; i < m; i++) {
            arr = in.readLine().split(" ");
            int u = Integer.parseInt(arr[0]) - 1;
            int v = Integer.parseInt(arr[1]) - 1;
            g[u].add(v);
            g[v].add(u);
            e.add(new Pair(u, v));
        }

        int[] ds = bfs(g, 0);
        int[] dt = bfs(g, n - 1);

        int[] cnt = new int[n];
        int[] idx = new int[n];

        List<Integer> ans = new ArrayList<Integer>();

        for (int i = 0; i < m; i++) {
            if (ds[e.get(i).u] + 1 + dt[e.get(i).v] == ds[n - 1]) {
                cnt[ds[e.get(i).u]]++;
                idx[ds[e.get(i).u]] = e.get(i).v;
            }
            if (ds[e.get(i).v] + 1 + dt[e.get(i).u] == ds[n - 1]) {
                cnt[ds[e.get(i).v]]++;
                idx[ds[e.get(i).v]] = e.get(i).u;
            }
        }

        for (int i = 0; i < m; i++) {
            if (cnt[ds[e.get(i).u]] == 1 && idx[ds[e.get(i).u]] == e.get(i).v
                    || cnt[ds[e.get(i).v]] == 1 && idx[ds[e.get(i).v]] == e.get(i).u) {
                ans.add(i);
            }
        }

        PrintWriter writer = new PrintWriter(new BufferedOutputStream(System.out));

        writer.println(ans.size());
        for (Integer an : ans) {
            writer.print((an + 1) + " ");
        }

        writer.close();
    }

    private static final class Pair {
        private int u;
        private int v;

        private Pair(int u, int v) {
            this.u = u;
            this.v = v;
        }
    }
}