#include <bits/stdc++.h>
using namespace std;
int n, tot = 1, m, tofa[200005], s[200005], tr[200005], f[200005], dep[200005],
       vis[100005], head[200005], go[200005], nex[200005];
vector<int> ans;
void add(int u, int v) {
  nex[++tot] = head[u];
  head[u] = tot;
  go[tot] = v;
}
void build(int u, int fa, int dp) {
  dep[u] = dep[fa] + 1;
  vis[u] = 1;
  f[u] = fa;
  for (int i = head[u]; i; i = nex[i]) {
    int v = go[i];
    if (v == fa || vis[v]) continue;
    tofa[v] = i;
    tr[i >> 1] = 1;
    build(v, u, dp + 1);
  }
}
void dfs(int u, int fa) {
  vis[u] = 1;
  for (int i = head[u]; i; i = nex[i]) {
    int v = go[i];
    if (v == fa || vis[v]) continue;
    dfs(v, u);
    s[u] += s[v];
  }
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    add(u, v);
    add(v, u);
  }
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) build(i, 0, 0);
  }
  for (int i = 1; i <= m; i++) {
    if (!tr[i]) {
      int u = go[i * 2], v = go[i * 2 + 1];
      if (dep[u] < dep[v]) swap(u, v);
      s[u]++;
      s[v]--;
    }
  }
  memset(vis, 0, sizeof(vis));
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) {
      dfs(i, 0);
    }
  }
  for (int i = 1; i <= m; i++) {
    if (tr[i]) continue;
    int u = go[i * 2], v = go[i * 2 + 1];
    if (dep[u] < dep[v]) swap(u, v);
    int tmp = u, bj = 0;
    while (1) {
      if (tmp == v) break;
      if (s[tmp] != 1) {
        bj = 1;
        break;
      }
      tmp = f[tmp];
    }
    if (bj == 0) {
      ans.push_back(i);
      while (1) {
        ans.push_back(tofa[u] >> 1);
        u = f[u];
        if (v == u) break;
      }
    }
  }
  sort(ans.begin(), ans.end());
  cout << ans.size() << "\n";
  for (int i = 0; i < ans.size(); i++) {
    cout << ans[i] << " ";
  }
  return 0;
}
