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 <class T>
bool umin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool umax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
int fup[100009], tin[100009], TIM, S, sz[100009], comp[100009];
vector<int> adj[100009], all[100009];
stack<int> st;
void dfs(int nd, int pr) {
  fup[nd] = tin[nd] = ++TIM;
  st.push(nd);
  for (int i = 0; i < (int)adj[nd].size(); i++) {
    int to = adj[nd][i];
    if (to == pr) continue;
    if (tin[to])
      umin(fup[nd], tin[to]);
    else {
      dfs(to, nd);
      umin(fup[nd], fup[to]);
    }
  }
  if (fup[nd] == tin[nd]) {
    S++;
    int aux;
    do {
      aux = st.top();
      st.pop();
      comp[aux] = S;
      sz[S]++;
    } while (aux != nd);
  }
}
pair<int, int> edge[100009];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
    edge[i] = make_pair(u, v);
  }
  for (int i = 1; i <= n; i++)
    if (!tin[i]) dfs(i, -1);
  for (int i = 1; i <= m; i++) {
    int u = edge[i].first, v = edge[i].second;
    if (comp[u] == comp[v]) all[comp[u]].push_back(i);
  }
  vector<int> ans;
  for (int i = 1; i <= S; i++)
    if (sz[i] == int(all[i].size())) {
      for (__typeof((all[i]).begin()) it = (all[i]).begin();
           it != (all[i]).end(); it++)
        ans.push_back(*it);
    }
  printf("%d\n", int(ans.size()));
  sort(ans.begin(), ans.end());
  for (__typeof((ans).begin()) it = (ans).begin(); it != (ans).end(); it++)
    printf("%d ", *it);
  puts("");
  return 0;
}
