#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
int n, m;
int deg[MAXN];
vector<pair<int, int>> graph[MAXN];
int up[MAXN], visit[MAXN], vtime;
vector<tuple<int, int, int>> stk;
int bcc_cnt;
set<int> bccverts[MAXN];
set<int> bccedges[MAXN];
void dfs(int nod, int par_edge) {
  up[nod] = visit[nod] = ++vtime;
  int child = 0;
  for (const auto& e : graph[nod]) {
    int next = e.first, edge_id = e.second;
    if (edge_id == par_edge) continue;
    if (visit[next] == 0) {
      stk.emplace_back(nod, next, edge_id);
      ++child;
      dfs(next, edge_id);
      if ((par_edge == -1 && child > 1) ||
          (par_edge != -1 && up[next] >= visit[nod])) {
        ++bcc_cnt;
        do {
          int lastnod, lastnext, lasteid;
          tie(lastnod, lastnext, lasteid) = stk.back();
          stk.pop_back();
          bccverts[bcc_cnt].insert(lastnext);
          bccedges[bcc_cnt].insert(lasteid);
          if (lastnod == nod && lastnext == next) break;
        } while (!stk.empty());
        bccverts[bcc_cnt].insert(nod);
      }
      up[nod] = min(up[nod], up[next]);
    } else {
      if (visit[next] <= visit[nod]) {
        stk.emplace_back(nod, next, edge_id);
      }
      up[nod] = min(up[nod], visit[next]);
    }
  }
}
void get_bcc() {
  vtime = 0;
  memset(visit, 0, sizeof(visit));
  bcc_cnt = 0;
  for (int i = 1; i <= n; ++i) {
    if (visit[i] == 0) {
      dfs(i, -1);
      if (!stk.empty()) {
        ++bcc_cnt;
        do {
          int lastnod, lastnext, lasteid;
          tie(lastnod, lastnext, lasteid) = stk.back();
          stk.pop_back();
          bccverts[bcc_cnt].insert(lastnext);
          bccedges[bcc_cnt].insert(lasteid);
        } while (!stk.empty());
        bccverts[bcc_cnt].insert(i);
      }
    }
  }
}
void proc() {
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    int a, b;
    cin >> a >> b;
    deg[a] += 1;
    deg[b] += 1;
    graph[a].emplace_back(b, i);
    graph[b].emplace_back(a, i);
  }
  get_bcc();
  vector<int> ans;
  for (int i = 1; i <= bcc_cnt; ++i) {
    if (bccverts[i].size() == bccedges[i].size()) {
      for (int e : bccedges[i]) ans.push_back(e);
    }
  }
  sort(ans.begin(), ans.end());
  cout << ans.size() << '\n';
  for (int e : ans) cout << e << ' ';
  cout << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  proc();
  return 0;
}
