#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int MAXN = 1e6 + 5, inf = 1e9;
const ll INF = 1e18;
const ld PI = 3.1415926535897932384626433832795;
int BC[MAXN], sz[MAXN], low[MAXN], pre[MAXN], num = 1, tim;
bool vis[MAXN], used[MAXN];
pair<int, int> E[MAXN];
vector<pair<int, int>> G[MAXN];
stack<int> St;
set<int> S[MAXN];
void dfs(int v, int p) {
  vis[v] = 1, pre[v] = tim++, low[v] = pre[v];
  for (auto e : G[v]) {
    int u = e.first, id = e.second;
    if (u == p) continue;
    if (!used[id]) {
      St.push(id);
      used[id] = 1;
    }
    if (!vis[u]) {
      dfs(u, v);
      low[v] = min(low[v], low[u]);
      if (low[u] >= pre[v]) {
        int x = St.top();
        while (x != id) {
          BC[x] = num;
          St.pop();
          x = St.top();
        }
        BC[x] = num++;
        St.pop();
      }
    } else
      low[v] = min(low[v], pre[u]);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout << setprecision(13) << fixed;
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    G[a].push_back({b, i});
    G[b].push_back({a, i});
    E[i] = {a, b};
  }
  for (int i = 1; i <= n; i++) {
    if (!low[i]) dfs(i, i);
  }
  for (int i = 0; i < m; i++) {
    sz[BC[i]]++;
    S[BC[i]].insert({E[i].first});
    S[BC[i]].insert({E[i].second});
  }
  for (int i = 1; i < num; i++) {
    if (S[i].size() == sz[i]) {
      S[0].insert(i);
    }
  }
  vector<int> res;
  for (int i = 0; i < m; i++) {
    if (S[0].find(BC[i]) == S[0].end()) continue;
    res.push_back(i + 1);
  }
  cout << res.size() << "\n";
  for (int i : res) cout << i << " ";
  cout << "\n";
}
