2 0
 100000 0
 8 9
1 2
2 3
3 4
4 1
5 6
6 7
7 8
8 5
6 8
 2 1
1 2
 11 9
5 9
8 5
11 3
11 1
3 4
7 11
3 1
11 2
7 2
 7 9
7 3
7 4
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 7 5
5 4
7 3
7 1
6 7
3 1
 7 8
1 2
2 3
3 4
4 1
3 5
5 6
6 7
7 3
 6 9
1 2
2 3
1 4
4 2
5 2
5 3
4 5
6 4
6 5
 7 9
1 2
2 4
4 3
3 1
2 3
4 5
5 6
6 7
7 4
 1 0
 6 7
1 2
2 3
3 1
3 4
4 5
5 6
6 4
 4 5
1 2
2 3
3 4
4 1
1 3
 100000 3
99998 99999
99999 100000
100000 99998

0

 0

 4
1 2 3 4 
 0

 6
3 4 6 7 8 9 
 9
1 2 3 4 5 6 7 8 9 
 3
2 3 5 
 8
1 2 3 4 5 6 7 8 
 0

 4
6 7 8 9 
 0

 6
1 2 3 5 6 7 
 0

 3
1 2 3 

import java.lang.reflect.Array;
import java.util.*;
import java.io.*;
import java.text.*;

public class CF_962_F{
    //SOLUTION BEGIN
    void pre() throws Exception{}
    void solve(int TC) throws Exception{
        int N = ni(), M = ni();
        int[] from = new int[M], to = new int[M];
        for(int i = 0; i< M; i++){
            from[i] = ni()-1;
            to[i] = ni()-1;
        }
        int[][][] g = makeS(N, M, from, to, true);
        boolean[] bridge = Bridge.bridges(g);
        int[] set = java.util.stream.IntStream.range(0, N).toArray();
        for(int i = 0; i< M; i++){
            if(bridge[i])continue;
            set[find(set, from[i])] = find(set, to[i]);
        }
        ArrayList<Integer> ans = new ArrayList<>();
        ArrayList<Integer>[] list = new ArrayList[N];
        int[] sz = new int[N];
        for(int i = 0; i< N; i++){
            list[i] = new ArrayList<>();
            sz[find(set, i)]++;
        }
        for(int i = 0; i< M; i++){
            if(bridge[i])continue;
            list[find(set, from[i])].add(i);
        }
        for(int i = 0; i< N; i++){
            if(sz[i] == list[i].size()){
                ans.addAll(list[i]);
            }
        }
        Collections.sort(ans);
        pn(ans.size());
        for(int x:ans)p(1+x);pn("");
    }
    static class Bridge{
        private static int time;
        private static int[] disc, low;
        private static boolean[] visited;

        public static boolean[] bridges(int[][][] graphWithEdgeInfo){
            int edgeCount = 0;
            for(int[][] row:graphWithEdgeInfo)edgeCount += row.length;
            return bridges(graphWithEdgeInfo, edgeCount/2);
        }

        public static boolean[] bridges(int[][][] graphWithEdgeInfo, int edgeCount){
            int NumberOfNodes = graphWithEdgeInfo.length;

            time = -1;
            disc = new int[NumberOfNodes];
            low = new int[NumberOfNodes];
            visited = new boolean[NumberOfNodes];
            java.util.Arrays.fill(low, 2*NumberOfNodes);

            boolean[] isBridge = new boolean[edgeCount];
            for(int i = 0; i< NumberOfNodes; i++)if(!visited[i] && graphWithEdgeInfo[i] != null)bridgeUtil(graphWithEdgeInfo, isBridge, i, -1);
            return isBridge;
        }

        private static void bridgeUtil(int[][][] g, boolean[] isBridge, int u, int parentEdge){
            visited[u] = true;
            disc[u] = low[u] = ++time;

            for(int[] edge: g[u]){
                int v = edge[0], edgeIndex = edge[1];
                if(parentEdge == edgeIndex)continue;

                if(visited[v])
                    low[u] = Math.min(low[u], disc[v]);
                else{
                    bridgeUtil(g, isBridge, v, edgeIndex);
                    low[u] = Math.min(low[u], low[v]);

                    if(low[v] > disc[u])isBridge[edgeIndex] = true;
                }
            }
        }
    }
    //SOLUTION END
    void hold(boolean b)throws Exception{if(!b)throw new Exception("Hold right there, Sparky!");}
    void exit(boolean b){if(!b)System.exit(0);}
    static void dbg(Object... o){System.err.println(Arrays.deepToString(o));}
    final long IINF = (long)1e17;
    final int INF = (int)1e9+2;
    DecimalFormat df = new DecimalFormat("0.00000000000");
    double PI = 3.141592653589793238462643383279502884197169399, eps = 1e-8;
    static boolean multipleTC = false, memory = true, fileIO = false;
    FastReader in;PrintWriter out;
    void run() throws Exception{
        long ct = System.currentTimeMillis();
        if (fileIO) {
            in = new FastReader("");
            out = new PrintWriter("");
        } else {
            in = new FastReader();
            out = new PrintWriter(System.out);
        }
        //Solution Credits: Taranpreet Singh
        int T = multipleTC? ni():1;
        pre();
        for (int t = 1; t <= T; t++) solve(t);
        out.flush();
        out.close();
        System.err.println(System.currentTimeMillis() - ct);
    }
    public static void main(String[] args) throws Exception{
        if(memory)new Thread(null, new Runnable() {public void run(){try{new CF_962_F().run();}catch(Exception e){e.printStackTrace();System.exit(1);}}}, "1", 1 << 28).start();
        else new CF_962_F().run();
    }
    int[][] make(int n, int e, int[] from, int[] to, boolean f){
        int[][] g = new int[n][];int[]cnt = new int[n];
        for(int i = 0; i< e; i++){
            cnt[from[i]]++;
            if(f)cnt[to[i]]++;
        }
        for(int i = 0; i< n; i++)g[i] = new int[cnt[i]];
        for(int i = 0; i< e; i++){
            g[from[i]][--cnt[from[i]]] = to[i];
            if(f)g[to[i]][--cnt[to[i]]] = from[i];
        }
        return g;
    }
    int[][][] makeS(int n, int e, int[] from, int[] to, boolean f){
        int[][][] g = new int[n][][];int[]cnt = new int[n];
        for(int i = 0; i< e; i++){
            cnt[from[i]]++;
            if(f)cnt[to[i]]++;
        }
        for(int i = 0; i< n; i++)g[i] = new int[cnt[i]][];
        for(int i = 0; i< e; i++){
            g[from[i]][--cnt[from[i]]] = new int[]{to[i], i, 0};
            if(f)g[to[i]][--cnt[to[i]]] = new int[]{from[i], i, 1};
        }
        return g;
    }
    int find(int[] set, int u){return set[u] = (set[u] == u?u:find(set, set[u]));}
    int digit(long s){int ans = 0;while(s>0){s/=10;ans++;}return ans;}
    long gcd(long a, long b){return (b==0)?a:gcd(b,a%b);}
    int gcd(int a, int b){return (b==0)?a:gcd(b,a%b);}
    int bit(long n){return (n==0)?0:(1+bit(n&(n-1)));}
    void p(Object... o){for(Object oo:o)out.print(oo+" ");}
    void pn(Object... o){for(int i = 0; i< o.length; i++)out.print(o[i]+(i+1 < o.length?" ":"\n"));}
    void pni(Object... o){for(Object oo:o)out.print(oo+" ");out.println();out.flush();}
    String n()throws Exception{return in.next();}
    String nln()throws Exception{return in.nextLine();}
    int ni()throws Exception{return Integer.parseInt(in.next());}
    long nl()throws Exception{return Long.parseLong(in.next());}
    double nd()throws Exception{return Double.parseDouble(in.next());}

    class FastReader{
        BufferedReader br;
        StringTokenizer st;
        public FastReader(){
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        public FastReader(String s) throws Exception{
            br = new BufferedReader(new FileReader(s));
        }

        String next() throws Exception{
            while (st == null || !st.hasMoreElements()){
                try{
                    st = new StringTokenizer(br.readLine());
                }catch (IOException  e){
                    throw new Exception(e.toString());
                }
            }
            return st.nextToken();
        }

        String nextLine() throws Exception{
            String str;
            try{
                str = br.readLine();
            }catch (IOException e){
                throw new Exception(e.toString());
            }
            return str;
        }
    }
}