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;
int n, m;
vector<int> g[100010];
struct TEdge {
  int u;
  int v;
  TEdge() {}
  TEdge(int foo, int bar) {
    u = foo;
    v = bar;
  }
  int findAnother(int foo) { return (u + v - foo); }
} Edge[100010];
bool CriticalEdge[100010];
int num[100010], low[100010], cnt;
void dfs(int u, int da) {
  num[u] = low[u] = ++cnt;
  for (int i = 0; i < (int)g[u].size(); ++i) {
    int id = g[u][i];
    int v = Edge[id].findAnother(u);
    if (v == da) continue;
    if (num[v])
      low[u] = min(low[u], num[v]);
    else {
      dfs(v, u);
      low[u] = min(low[u], low[v]);
      if (low[v] >= num[v]) CriticalEdge[id] = true;
    }
  }
}
int nVertice, nEdge;
vector<int> lis, Candidate;
void find_answer(int u) {
  num[u] = 1;
  nVertice++;
  for (int i = 0; i < (int)g[u].size(); ++i) {
    int id = g[u][i];
    if (CriticalEdge[id]) continue;
    int v = Edge[id].findAnother(u);
    if (u < v) nEdge++, Candidate.push_back(id);
    if (!num[v]) find_answer(v);
  }
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    int u, v;
    cin >> u >> v;
    Edge[i] = TEdge(u, v);
    g[u].push_back(i);
    g[v].push_back(i);
  }
  for (int i = 1; i <= n; ++i)
    if (!num[i]) dfs(i, 0);
  for (int i = 1; i <= n; ++i) num[i] = 0;
  for (int i = 1; i <= n; ++i) {
    nVertice = nEdge = 0;
    if (!num[i]) find_answer(i);
    if (nVertice == nEdge)
      for (int j = 0; j < (int)Candidate.size(); ++j)
        lis.push_back(Candidate[j]);
    Candidate.clear();
  }
  sort(lis.begin(), lis.end());
  cout << (int)lis.size() << endl;
  for (int i = 0; i < (int)lis.size(); ++i) cout << lis[i] << " ";
  return 0;
}
