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 mod = (int)1e9 + 7;
const int maxn = (int)1e5 + 10;
const long long int inf = std::numeric_limits<long long int>::max();
vector<pair<int, int> > adj[maxn];
pair<int, int> parent[maxn];
int dp1[maxn], lvl[maxn], dp2[maxn], root;
vector<int> ans;
void dfs(int u) {
  for (auto e : adj[u]) {
    int v, id;
    tie(v, id) = e;
    if (v == parent[u].first) continue;
    if (lvl[v] != 0 && lvl[v] < lvl[u]) {
      dp1[v]--;
      dp1[u]++;
    } else if (lvl[v] == 0) {
      lvl[v] = lvl[u] + 1;
      parent[v] = {u, id};
      dfs(v);
      dp1[u] += dp1[v];
    }
  }
}
void dfs2(int u, vector<int> &acum) {
  int pos = acum.size();
  acum.push_back(dp1[u] + (acum.empty() ? 0 : acum.back()));
  for (auto e : adj[u]) {
    int v, id;
    tie(v, id) = e;
    if (v == parent[u].first) continue;
    if (lvl[v] != 0 && lvl[v] < lvl[u]) {
      int dif = lvl[u] - lvl[v];
      assert(pos - dif >= 0);
      int cuantas = acum[pos] - acum[pos - dif];
      if (cuantas == dif) {
        ans.push_back(id);
        dp2[v]--;
        dp2[u]++;
      }
    } else if (lvl[v] == 0) {
      lvl[v] = lvl[u] + 1;
      parent[v] = {u, id};
      dfs2(v, acum);
      dp2[u] += dp2[v];
    }
  }
  if (u != root && dp2[u] == 1) {
    ans.push_back(parent[u].second);
  }
  acum.pop_back();
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back({v, i});
    adj[v].push_back({u, i});
  }
  for (int i = 1; i <= n; i++) {
    if (lvl[i] == 0) {
      root = i;
      lvl[i] = 1;
      dfs(i);
    }
  }
  for (int i = 1; i <= n; i++) {
    lvl[i] = 0;
    parent[i] = {0, 0};
  }
  vector<int> aux, aux2;
  for (int i = 1; i <= n; i++) {
    if (lvl[i] == 0) {
      root = i;
      lvl[i] = 1;
      aux.clear();
      dfs2(i, aux);
    }
  }
  sort((ans).begin(), (ans).end());
  cout << ans.size() << '\n';
  for (int x : ans) cout << x << " ";
  cout << '\n';
  return 0;
}
