#include <bits/stdc++.h>
using namespace std;
const int maxn = 100009;
const int MOD = 1e9 + 7;
vector<pair<int, int>> V[maxn], E;
int fa[maxn], a[maxn], b[maxn], dfn[maxn], idx, fae[maxn];
void dfs(int u, int f) {
  fa[u] = f;
  dfn[u] = ++idx;
  for (auto [v, id] : V[u]) {
    if (!dfn[v]) dfs(v, u), fae[v] = id;
  }
}
void dfs2(int u) {
  for (auto i : V[u]) {
    int v = i.first;
    if (fa[v] == u) {
      dfs2(v);
      a[u] += a[v];
    }
  }
  if (a[u] != -1) b[u] = 1;
}
void dfs3(int u) {
  for (auto i : V[u]) {
    int v = i.first;
    if (fa[v] == u) {
      b[v] += b[u];
      dfs3(v);
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  E.resize(m);
  for (int i = 0; i < m; ++i) {
    cin >> E[i].first >> E[i].second;
    V[E[i].first].emplace_back(E[i].second, i);
    V[E[i].second].emplace_back(E[i].first, i);
  }
  vector<int> rt;
  for (int i = 1; i <= n; ++i)
    if (!dfn[i]) dfs(i, i), rt.push_back(i);
  for (int i = 0; i < m; ++i) {
    int u = E[i].first, v = E[i].second;
    if (fa[u] == v || fa[v] == u) continue;
    if (dfn[u] > dfn[v]) swap(u, v);
    a[u]++;
    a[v]--;
  }
  for (int i : rt) dfs2(i);
  for (int i : rt) dfs3(i);
  vector<int> ans;
  for (int i = 0; i < m; ++i) {
    int u = E[i].first, v = E[i].second;
    if (fa[u] == v || fa[v] == u) continue;
    if (dfn[u] > dfn[v]) swap(u, v);
    if (b[u] == b[v]) {
      ans.push_back(i);
      while (v != u) {
        ans.push_back(fae[v]);
        v = fa[v];
      }
    }
  }
  sort(ans.begin(), ans.end());
  cout << ((int)(ans).size()) << '\n';
  for (int i : ans) cout << i + 1 << " ";
  cout << '\n';
  return 0;
}
