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, Q;
map<int, int> id[1000005];
vector<int> Adj[1000005];
vector<int> ans;
int p[1000005];
int dfn[1000005], tt = 0;
int low[1000005];
stack<int> st;
int cnt[1000005];
bool cmp(const int& a, const int& b) { return dfn[a] < dfn[b]; }
void dfs(int u) {
  dfn[u] = low[u] = ++tt;
  st.push(u);
  int v, x, y;
  for (int k = 0; k < Adj[u].size(); k++) {
    v = Adj[u][k];
    if (!dfn[v]) {
      p[v] = u;
      dfs(v);
      low[u] = min(low[u], low[v]);
      if (dfn[u] < low[v]) {
        st.pop();
      }
      if (dfn[u] == low[v]) {
        int n = 0;
        vector<int> vec;
        vec.push_back(u);
        while (1) {
          x = st.top();
          st.pop();
          vec.push_back(x);
          n += cnt[x];
          if (x == v) break;
        }
        if (n == 1) {
          sort(vec.begin(), vec.end(), cmp);
          vec.push_back(u);
          for (int k = 0; k < vec.size() - 1; k++) {
            x = vec[k];
            y = vec[k + 1];
            ans.push_back(id[x][y]);
          }
        }
      }
    } else if (v != p[u]) {
      if (dfn[v] < dfn[u]) ++cnt[u];
      low[u] = min(low[u], dfn[v]);
    }
  }
}
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(v);
    Adj[v].push_back(u);
    id[u][v] = id[v][u] = i;
  }
  for (int i = 1; i <= N; i++) {
    if (!dfn[i]) dfs(i);
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", ans.size());
  for (int k = 0; k < ans.size(); k++) {
    printf("%d ", ans[k]);
  }
  return 0;
}
