#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const long long mod = 1e9 + 7;
const long long inf = 1e18 + 10;
int mark[N], h[N], f[N], g[N], ps[N], res[N];
vector<pair<int, int> > adj[N];
void dfs0(int v) {
  mark[v] = 1;
  for (pair<int, int> e : adj[v]) {
    int u = e.first;
    if (!mark[u])
      h[u] = h[v] + 1, dfs0(u);
    else if (h[v] < h[u])
      f[u]++, f[v]--;
  }
}
void dfs1(int v) {
  mark[v] = 1;
  for (pair<int, int> e : adj[v])
    if (!mark[e.first]) dfs1(e.first), f[v] += f[e.first];
}
void dfs2(int v) {
  mark[v] = 1;
  ps[v] += (2 <= f[v]);
  for (pair<int, int> e : adj[v])
    if (!mark[e.first]) ps[e.first] = ps[v], dfs2(e.first);
}
void dfs3(int v) {
  mark[v] = 1;
  for (pair<int, int> e : adj[v]) {
    int u = e.first;
    if (!mark[u])
      dfs3(u);
    else if (h[v] < h[u] && 1 <= ps[u] - ps[v])
      g[u]++, g[v]--;
  }
}
void dfs4(int v) {
  mark[v] = 1;
  for (pair<int, int> e : adj[v])
    if (!mark[e.first]) dfs4(e.first), g[v] += g[e.first];
}
void dfs5(int v) {
  mark[v] = 1;
  for (pair<int, int> e : adj[v]) {
    int u = e.first, id = e.second;
    if (!mark[u])
      dfs5(u), res[id] = (f[u] == 1 && g[u] == 0);
    else if (h[v] < h[u])
      res[id] = (f[u] == 1 && g[u] == 0);
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back(make_pair(v, i));
    adj[v].push_back(make_pair(u, i));
  }
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs0(i);
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs1(i);
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs2(i);
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs3(i);
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs4(i);
  memset(mark, 0, sizeof mark);
  for (int i = 1; i <= n; i++)
    if (!mark[i]) dfs5(i);
  int cnt = 0;
  for (int i = 1; i <= m; i++)
    if (res[i]) cnt++;
  cout << cnt << '\n';
  for (int i = 1; i <= m; i++)
    if (res[i]) cout << i << ' ';
  return 0;
}
