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;
template <int SZ>
struct BCC {
  int N, ti = 0;
  vector<int> adj[SZ];
  int disc[SZ], low[SZ], comp[SZ], par[SZ];
  vector<vector<pair<int, int>>> fin;
  vector<pair<int, int>> st;
  void addEdge(int u, int v) { adj[u].push_back(v), adj[v].push_back(u); }
  void BCCutil(int u) {
    disc[u] = low[u] = ti++;
    int child = 0;
    for (int i : adj[u])
      if (i != par[u]) {
        if (disc[i] == -1) {
          child++;
          par[i] = u;
          st.push_back({u, i});
          BCCutil(i);
          low[u] = min(low[u], low[i]);
          if ((disc[u] == 0 && child > 1) ||
              (disc[u] != 0 && disc[u] <= low[i])) {
            vector<pair<int, int>> tmp;
            while (st.back() != make_pair(u, i))
              tmp.push_back(st.back()), st.pop_back();
            tmp.push_back(st.back()), st.pop_back();
            fin.push_back(tmp);
          }
        } else if (disc[i] < disc[u]) {
          low[u] = min(low[u], disc[i]);
          st.push_back({u, i});
        }
      }
  }
  void bcc() {
    for (int i = 1; i < N + 1; i++) par[i] = disc[i] = low[i] = -1;
    for (int i = 1; i < N + 1; i++)
      if (disc[i] == -1) {
        BCCutil(i);
        if (!st.empty()) fin.push_back(st);
        st.clear();
      }
  }
};
const int MAX_N = 100010;
int n, m;
map<pair<int, int>, int> ed;
bool works[MAX_N];
BCC<MAX_N> thing;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    thing.addEdge(a, b);
    ed[make_pair(a, b)] = i + 1;
  }
  thing.N = m;
  thing.bcc();
  vector<int> res;
  for (auto v : thing.fin) {
    set<int> s;
    for (pair<int, int> p : v) {
      s.insert(p.first);
      s.insert(p.second);
    }
    if ((int)s.size() == (int)v.size()) {
      for (pair<int, int> p : v) works[ed[p]] = 1;
    }
  }
  for (int i = 1; i < m + 1; i++)
    if (works[i]) res.push_back(i);
  cout << (int)res.size() << "\n";
  for (int i = 0; i < (int)res.size(); i++) {
    if (i != 0) cout << " ";
    cout << res[i];
  }
  cout << "\n";
}
