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;
struct edge {
  int u, v, second;
  edge() {}
  edge(int a, int b, int c) {
    u = a;
    v = b;
    second = c;
  }
};
vector<edge> adj[100005];
int N, M;
int low[100005], disc[100005], art[100005], par[100005];
int times = 1;
bitset<100005> vis;
stack<edge> st;
vector<int> ans;
set<int> V, E;
void DFS(int u, int p) {
  low[u] = disc[u] = times++;
  for (edge e : adj[u]) {
    int v = e.u;
    if (!disc[v]) {
      st.push(e);
      DFS(v, u);
      low[u] = min(low[u], low[v]);
    } else if (!vis[e.second]) {
      st.push(e);
      low[u] = min(low[u], disc[v]);
    }
  }
  if (low[u] == disc[p]) {
    V.clear();
    E.clear();
    while (1) {
      edge now = st.top();
      st.pop();
      V.insert(now.u);
      V.insert(now.v);
      E.insert(now.second);
      vis[now.second] = 1;
      if (now.v == p) break;
    }
    if (E.size() == V.size()) {
      for (auto i : E) {
        ans.push_back(i);
      }
    }
  }
}
int main() {
  scanf("%d %d", &N, &M);
  int u, v;
  for (int i = 1; i <= M; i++) {
    scanf("%d %d", &u, &v);
    adj[u].push_back(edge(v, u, i));
    adj[v].push_back(edge(u, v, i));
  }
  for (int i = 1; i <= N; i++) {
    if (!disc[i]) {
      DFS(i, 0);
    }
  }
  printf("%d\n", ans.size());
  if (!ans.size()) {
    return 0;
  }
  sort(ans.begin(), ans.end());
  for (int i : ans) {
    cout << i << " ";
  }
}
