#include <bits/stdc++.h>
using namespace std;
const int NN = 1e5 + 10;
int head[NN], to[NN << 1], nxt[NN << 1];
int E = 0, ind, cnt, top;
int low[NN], vst[NN], st[NN << 1];
vector<int> con[NN], ans;
int pv[NN << 1], id[NN << 1];
int add(int u, int v, int w) {
  nxt[E] = head[u];
  pv[E] = u;
  to[E] = v;
  id[E] = w;
  head[u] = E++;
  nxt[E] = head[v];
  pv[E] = v;
  to[E] = u;
  id[E] = w;
  head[v] = E++;
}
void dfs(int u, int pa = 0) {
  vst[u] = low[u] = ++ind;
  for (int e = head[u]; ~e; e = nxt[e]) {
    int v = to[e];
    if (vst[v] < vst[u]) st[top++] = e;
    if (!vst[v]) {
      dfs(v, u), low[u] = min(low[u], low[v]);
      if (low[v] >= vst[u]) {
        con[++cnt].clear();
        do --top, con[cnt].push_back(st[top] & 1 ? st[top] ^ 1 : st[top]);
        while (st[top] != e);
        sort(con[cnt].begin(), con[cnt].end());
        con[cnt].resize(unique(con[cnt].begin(), con[cnt].end()) -
                        con[cnt].begin());
      }
    } else if (pa != v)
      low[u] = min(low[u], vst[v]);
  }
}
int main() {
  memset(head, -1, sizeof head);
  int n, m;
  cin >> n >> m;
  for (int i = 1, u, v; i <= m; i++) cin >> u >> v, add(u, v, i);
  for (int i = 1; i <= n; i++)
    if (!vst[i]) dfs(i);
  for (int i = 1; i <= cnt; i++) {
    set<int> st;
    for (auto r : con[i]) st.insert(to[r]), st.insert(pv[r]);
    if (st.size() == con[i].size())
      for (auto r : con[i]) ans.push_back(id[r]);
  }
  cout << ans.size() << endl;
  sort(ans.begin(), ans.end());
  for (auto &r : ans) printf("%d ", r);
  return 0;
}
