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 N = 100010;
vector<int> son[N], root, pe, ans;
vector<pair<int, int>> e[N];
pair<int, int> E[N], par[N];
int cnt[N], cnt2[N], dfn[N];
int n, m, u, v, dt;
void dfs(int u) {
  dfn[u] = ++dt;
  for (auto p : e[u]) {
    int v = p.first, id = p.second;
    if (!dfn[v]) {
      dfs(v);
      son[u].push_back(v);
      par[v] = make_pair(u, id);
    } else if (dfn[u] < dfn[v]) {
      cnt[u]--;
      cnt[v]++;
      pe.push_back(id);
    }
  }
}
void dfs2(int u) {
  for (auto v : son[u]) {
    dfs2(v);
    cnt[u] += cnt[v];
  }
  cnt2[u] = cnt[u] >= 2;
}
void dfs3(int u) {
  for (auto v : son[u]) {
    cnt2[v] += cnt2[u];
    dfs3(v);
  }
}
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d %d", &u, &v);
    E[i] = make_pair(u, v);
    e[u].push_back(make_pair(v, i));
    e[v].push_back(make_pair(u, i));
  }
  for (int i = 1; i <= n; i++)
    if (!dfn[i]) {
      dfs(i);
      root.push_back(i);
    }
  for (int u : root) dfs2(u);
  for (int u : root) dfs3(u);
  for (int p : pe) {
    int u = E[p].first, v = E[p].second;
    if (dfn[v] < dfn[u]) swap(u, v);
    if (cnt2[u] == cnt2[v]) {
      ans.push_back(p);
      while (v != u) {
        ans.push_back(par[v].second);
        v = par[v].first;
      }
    }
  }
  sort(ans.begin(), ans.end());
  printf("%d\n", (int)ans.size());
  for (int p : ans) printf("%d ", p);
  return 0;
}
