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;
const int MAXN = 100005;
int disc[MAXN], low[MAXN];
vector<int> adj[MAXN];
stack<pair<int, int> > S;
vector<vector<pair<int, int> > > allcomponent;
map<pair<int, int>, int> urutan;
void dfs(int now, int par) {
  disc[now] = low[now] = disc[par] + 1;
  for (auto nxt : adj[now]) {
    if (nxt == par) continue;
    if (disc[now] > disc[nxt]) S.push({now, nxt});
    if (disc[nxt] != 0)
      low[now] = min(low[now], disc[nxt]);
    else {
      dfs(nxt, now);
      low[now] = min(low[now], low[nxt]);
      if (low[nxt] >= disc[now]) {
        vector<pair<int, int> > component;
        while (!S.empty() && (S.top().first != now || S.top().second != nxt)) {
          component.push_back(S.top());
          S.pop();
        }
        component.push_back(S.top());
        S.pop();
        allcomponent.push_back(component);
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, m, u, v;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    cin >> u >> v;
    adj[u].push_back(v);
    adj[v].push_back(u);
    urutan[{u, v}] = i;
    urutan[{v, u}] = i;
  }
  for (int i = 1; i <= n; i++)
    if (disc[i] == 0) dfs(i, 0);
  vector<int> ans;
  for (auto isi : allcomponent) {
    set<int> node;
    for (auto edge : isi) {
      node.insert(edge.first);
      node.insert(edge.second);
    }
    if (node.size() == isi.size()) {
      for (auto edge : isi) ans.push_back(urutan[edge]);
    }
  }
  sort(ans.begin(), ans.end());
  ans.erase(unique(ans.begin(), ans.end()), ans.end());
  cout << ans.size() << '\n';
  for (auto isi : ans) cout << isi << " ";
  cout << '\n';
  return 0;
}
