#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, m, cnt, head[N], dfn[N], dep[N], s[N], f[N], g[N], fa[N];
bool vis[N];
struct edge {
  int to, next;
  bool tag;
} e[N << 1];
int find(int x) {
  if (f[x] == x)
    return x;
  else
    return f[x] = find(f[x]);
}
void add(int u, int v) {
  e[++cnt].to = v;
  e[cnt].next = head[u];
  head[u] = cnt;
}
void dfs1(int x, int fu, int d) {
  vis[x] = 1;
  dep[x] = d;
  for (int i = head[x]; i; i = e[i].next) {
    int v = e[i].to;
    if (v == fu) continue;
    if (!vis[v])
      fa[v] = x, dfn[v] = i, dfs1(v, x, d + 1);
    else if (dep[v] < dep[x])
      s[x]++, s[v]--;
  }
}
void dfs2(int x, int fu) {
  vis[x] = 1;
  for (int i = head[x]; i; i = e[i].next) {
    int v = e[i].to;
    if (v == fu) continue;
    if (!vis[v]) dfs2(v, x), s[x] += s[v];
  }
}
void dfs3(int x, int fu) {
  vis[x] = 1;
  g[x] = (s[x] > 1) + g[fu];
  for (int i = head[x]; i; i = e[i].next) {
    int v = e[i].to;
    if (v == fu) continue;
    if (!vis[v])
      dfs3(v, x);
    else if (dep[v] < dep[x] && g[x] == g[v]) {
      int y = find(x);
      e[i].tag = e[i ^ 1].tag = 1;
      while (dep[y] > dep[v]) {
        e[dfn[y]].tag = e[dfn[y] ^ 1].tag = 1;
        f[y] = find(fa[y]);
        y = find(y);
      }
    }
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> m;
  cnt = 1;
  for (int i = 1, x, y; i <= m; i++) cin >> x >> y, add(x, y), add(y, x);
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs1(i, 0, 1);
  memset(vis, 0, sizeof(vis));
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs2(i, 0);
  memset(vis, 0, sizeof(vis));
  for (int i = 1; i <= n; i++) f[i] = i;
  for (int i = 1; i <= n; i++)
    if (!vis[i]) dfs3(i, 0);
  int ans = 0;
  for (int i = 2; i <= cnt; i += 2) ans += e[i].tag;
  cout << ans << endl;
  for (int i = 2; i <= cnt; i += 2)
    if (e[i].tag) cout << i / 2 << " ";
  return 0;
}
