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 = 1e5 + 5;
int n, m, a[maxn], h[maxn], b[maxn], c[maxn], par[maxn];
vector<int> adj[maxn];
vector<pair<int, int> > edge;
bool vis[maxn];
void dfs1(int v = 0, int hi = 0) {
  h[v] = hi;
  vis[v] = 1;
  for (auto u : adj[v])
    if (!vis[u])
      dfs1(u, hi + 1), par[u] = v;
    else if (h[u] < h[v] - 1) {
      a[v]++;
      a[u]--;
    }
}
void dfs2(int v = 0) {
  b[v] = a[v];
  vis[v] = 1;
  for (auto u : adj[v])
    if (!vis[u]) dfs2(u), b[v] += b[u];
}
void dfs3(int v = 0, int x = 0) {
  c[v] = x + (b[v] > 1);
  vis[v] = 1;
  for (auto u : adj[v])
    if (!vis[u]) dfs3(u, x + (b[v] > 1));
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    adj[x].push_back(y);
    adj[y].push_back(x);
    edge.push_back({x, y});
  }
  adj[0].push_back(1);
  dfs1();
  memset(vis, 0, maxn);
  dfs2();
  memset(vis, 0, maxn);
  dfs3();
  for (auto e : edge) {
    if (abs(h[e.first] - h[e.second]) == 1) continue;
    if (h[e.first] > h[e.second]) swap(e.first, e.second);
    int x = abs(c[e.second] - c[e.first]);
    if (x > 0) {
      a[e.second] += 3, a[par[e.first]] -= 3;
    }
  }
  memset(vis, 0, maxn);
  dfs2();
  vector<int> ans;
  int i = 1;
  for (auto e : edge) {
    if (h[e.first] > h[e.second]) swap(e.first, e.second);
    if (b[e.second] == 1) ans.push_back(i);
    i++;
  }
  cout << ans.size() << '\n';
  for (auto e : ans) cout << e << " ";
  cout << '\n';
}
