#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr ll LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

template <typename CostType>
struct Edge {
  int src, dst; CostType cost;
  Edge(int src, int dst, CostType cost = 0) : src(src), dst(dst), cost(cost) {}
  inline bool operator<(const Edge &x) const {
    return cost != x.cost ? cost < x.cost : dst != x.dst ? dst < x.dst : src < x.src;
  }
  inline bool operator<=(const Edge &x) const { return !(x < *this); }
  inline bool operator>(const Edge &x) const { return x < *this; }
  inline bool operator>=(const Edge &x) const { return !(*this < x); }
};

template <typename CostType>
struct Lowlink {
  using E = Edge<CostType>;

  std::vector<std::vector<E>> graph;
  std::vector<int> ap;
  std::vector<E> bridge;

  Lowlink(const std::vector<std::vector<E>> &graph) : graph(graph) {
    int n = graph.size();
    order.assign(n, -1);
    lowlink.resize(n);
    int tm = 0;
    for (int i = 0; i < n; ++i) {
      if (order[i] == -1) dfs(-1, i, tm);
    }
    // std::sort(ap.begin(), ap.end());
    // std::sort(bridge.begin(), bridge.end(), [](const E &a, const E &b) -> bool {
    //   return a.src != b.src ? a.src < b.src : a.dst != b.dst ? a.dst < b.dst : a.cost < b.cost;
    // });
  }

  std::vector<int> order, lowlink;
private:
  void dfs(int par, int ver, int &tm) {
    order[ver] = lowlink[ver] = tm++;
    int cnt = 0;
    bool is_ap = false;
    for (const E &e : graph[ver]) {
      if (order[e.dst] == -1) {
        ++cnt;
        dfs(ver, e.dst, tm);
        if (lowlink[e.dst] < lowlink[ver]) lowlink[ver] = lowlink[e.dst];
        if (order[ver] <= lowlink[e.dst]) {
          is_ap = true;
          if (order[ver] < lowlink[e.dst]) bridge.emplace_back(std::min(ver, e.dst), std::max(ver, e.dst), e.cost);
        }
      } else if (e.dst != par) {
        if (order[e.dst] < lowlink[ver]) lowlink[ver] = order[e.dst];
      }
    }
    if (par == -1) {
      if (cnt >= 2) ap.emplace_back(ver);
    } else {
      if (is_ap) ap.emplace_back(ver);
    }
  }
};

int main() {
  int n; cin >> n;
  vector<vector<Edge<bool>>> graph(n);
  map<pair<int, int>, int> mp;
  REP(i, n) {
    int a, b; cin >> a >> b; --a; --b;
    if (a > b) swap(a, b);
    mp[{a, b}] = i;
    graph[a].emplace_back(a, b);
    graph[b].emplace_back(b, a);
  }
  set<int> st;
  REP(i, n) st.emplace(i);
  for (auto &e : Lowlink(graph).bridge) {
    int p = e.src, q = e.dst;
    if (p > q) swap(p, q);
    st.erase(mp[{p, q}]);
  }
  vector<int> ans(st.begin(), st.end());
  int k = ans.size();
  cout << k << '\n';
  REP(i, k) cout << ans[i] + 1 << " \n"[i + 1 == k];
  return 0;
}