#include <bits/stdc++.h>
using namespace std;
int T;
const int N = 110000;
int a[N], b[N], vis[N], cnt[N], cnt1[N], p[N];
vector<int> V, adj[N], con[N];
void dfs(int u, int pe) {
  vis[u] = ++T;
  for (int e : adj[u]) {
    if (e == pe) continue;
    int v = a[e] ^ b[e] ^ u;
    if (!vis[v]) {
      con[u].push_back(v);
      p[v] = e;
      dfs(v, e);
    } else if (vis[v] < vis[u]) {
      V.push_back(e);
      if (a[e] == v) swap(a[e], b[e]);
      cnt[u]++;
      cnt[v]--;
    }
  }
}
void dfs1(int u) {
  vis[u] = 1;
  for (int v : con[u]) {
    dfs1(v);
    cnt[u] += cnt[v];
  }
  cnt1[u] = cnt[u] >= 2;
}
void dfs2(int u) {
  vis[u] = 1;
  for (int v : con[u]) {
    cnt1[v] += cnt1[u];
    dfs2(v);
  }
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++)
    scanf("%d%d", &a[i], &b[i]), adj[a[i]].push_back(i), adj[b[i]].push_back(i);
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs(i, 0);
  memset(vis, 0, sizeof vis);
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs1(i);
  memset(vis, 0, sizeof vis);
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs2(i);
  vector<int> ans;
  for (int e : V)
    if (cnt1[a[e]] == cnt1[b[e]]) {
      ans.push_back(e);
      int u = a[e], v = b[e];
      while (u != v) {
        ans.push_back(p[u]);
        int f = p[u];
        u ^= a[f] ^ b[f];
      }
    }
  sort(ans.begin(), ans.end());
  cout << ans.size() << endl;
  for (int e : ans) printf("%d ", e);
  return 0;
}
