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 


#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef vector<str> vstr;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back 
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define rsz resize 
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)
	
const double EPS = 1e-9;
const int MOD = 1e9+7; // 998244353;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

#ifdef DEBUG
#define DBG if(1)
#else
#define DBG if(0)
#endif

#define dbg(x) cout << "(" << #x << " : " << x << ")" << endl;
// ostreams
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}
// istreams
template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }
template<class T, class U>
istream& operator>>(istream& in, pair<T, U> &p){ in >> p.ff >> p.ss; return in; }
//searches
template<typename T, typename U>
T bsl(T lo, T hi, U f){ hi++; T mid; while(lo < hi){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid+1; } return lo; }
template<typename U>
double bsld(double lo, double hi, U f, double p = 1e-9){ int r = 3 + (int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid; } return (lo + hi)/2; }
template<typename T, typename U>
T bsh(T lo, T hi, U f){ lo--; T mid; while(lo < hi){ mid = (lo + hi + 1)/2; f(mid) ? lo = mid : hi = mid-1; } return lo; }
template<typename U>
double bshd(double lo, double hi, U f, double p = 1e-9){ int r = 3+(int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? lo = mid : hi = mid; } return (lo + hi)/2; }
// some more utility functions
template<typename T>
pair<T, int> get_min(vector<T> &v){ typename vector<T> :: iterator it = min_element(v.begin(), v.end()); return mp(*it, it - v.begin());}
template<typename T>
pair<T, int> get_max(vector<T> &v){ typename vector<T> :: iterator it = max_element(v.begin(), v.end()); return mp(*it, it - v.begin());}        
template<typename T> bool ckmin(T& a, const T& b){return b < a ? a = b , true : false;}
template<typename T> bool ckmax(T& a, const T& b){return b > a ? a = b, true : false;}

template<typename T>
struct edge{
    int src;
    int dest;
    T cost;
};
template<typename T>
class graph{
    public: 
    vector<edge<T>> edges;
    vector<vector<int>> adj;
    int n;
    graph(){};
    graph(int _n){
        n = _n;
        adj.resize(n);
    }
};

template<typename T>
class undigraph : public graph<T>{
    public:
        using graph<T>::edges;
        using graph<T>::adj;
        using graph<T>::n;
        undigraph() : graph<T>(){};
        undigraph(int _n) : graph<T>(_n){};

        int add_edge(int src, int dest, T cost = 1){
            int id = edges.size();
            edges.push_back({src, dest, cost});
            adj[src].push_back(id);
            adj[dest].push_back(id);
            return id;
        }
};
    
int main(){
 	ios_base::sync_with_stdio(false);
 	cin.tie(NULL); cout.tie(NULL);
    int n, m; cin >> n >> m;
    undigraph<int> g(n);
    REP(i, m){
        int a, b; 
        cin >> a >> b;
        --a; --b;
        g.add_edge(a, b);
    }
    vector<bool> is_bridge(n, false);
    vi in(n, -1);
    vi low(n, INF);
    int t = 0;
    function<void(int, int)> dfs = [&](int v, int p){
        in[v] = t++;
        for(int id : g.adj[v]){
            auto e = g.edges[id];
            int oth = e.src ^ e.dest ^ v;
            if(oth == p) continue;
            if(in[oth] == -1){
                dfs(oth, v);
                if(low[oth] > in[v]){
                    is_bridge[id] = true;
                }
                low[v] = min(low[v], low[oth]);
            }
            else if(in[oth] < in[v]){
                low[v] = min(low[v], in[oth]);
            }
        } 
    };
    REP(i, n){
        if(in[i] == -1)
            dfs(i, -1);
    }	
    // biconnected components -> separated by bridges; if deg of one is > 2 then all edges in the component are bad
    // also bridges bad
    vector<int> component(n, -1);
    vector<int> ECC(m, -1);
    int comp_id = 0;
    function<void(int)> bcc = [&](int v){
        component[v] = comp_id;
        for(int id : g.adj[v]){
            auto e = g.edges[id];
            int oth = e.src ^ e.dest ^ v;
            if(!is_bridge[id]){
                ECC[id] = comp_id;
            }
            if(component[oth] == -1)
                bcc(oth);
        }
    };
    REP(i, n){ 
        if(component[i] == -1){
            bcc(i);
            comp_id++;
        }
    }
    vi deg(n, 0);
    vector<bool> ok(n, true);
    REP(i, n){
        for(int id : g.adj[i]){
            if(ECC[id] == component[i]) deg[i]++;
        }
        if(deg[i] > 2)
            ok[component[i]] = false;
    }
    vi ans;
    REP(i, m){
        if(is_bridge[i]) continue;
        if(ok[ECC[i]]) ans.pb(i); 
    }
    cout << ans.size() << endl;
    REP(i, ans.size()) cout << ans[i]+1 << " ";
    cout << "\n"; 
    return 0;
}
