#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <tuple>
#include <vector>
using namespace std;
using ll = int64_t;
#define rep(i, j, n) for (int i = j; i < (n); ++i)
#define rrep(i, j, n) for (int i = (n)-1; j <= i; --i)

template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T>& a) {
  os << "{";
  for (size_t i = 0; i < a.size(); ++i) os << (i > 0 ? "," : "") << a[i];
  return os << "}";
}
[[maybe_unused]] constexpr ll MOD = 1000000007;
[[maybe_unused]] constexpr int INF = 0x3f3f3f3f;
[[maybe_unused]] constexpr ll INFL = 0x3f3f3f3f3f3f3f3fLL;

struct Edge {
  int from, to;
  Edge(int f, int t) : from(f), to(t) {}
};

using Edges = vector<Edge>;
using Graph = vector<Edges>;

class LowLink {
public:
  LowLink(int n) : mGraph(n), mOrd(n), mLow(n), mUsed(n, false) {}
  void add_edge(int u, int v) {
    mGraph[u].emplace_back(u, v);
    mGraph[v].emplace_back(v, u);
  }
  // e(u,v)が橋　<=> ord[u] < low[v]
  // 頂点vが関節点 <=> ord[u] <= low[v]となるvの子uが存在
  int dfs(int v, int pv, int k) {
    mUsed[v] = true;
    mOrd[v] = mLow[v] = k++; // 訪れた順
    bool is_articulation = false;
    int cnt = 0;
    for (Edge nv : mGraph[v]) {
      if (!mUsed[nv.to]) { // まだ訪れてない
        ++cnt;
        k = dfs(nv.to, v, k);
        mLow[v] = min(mLow[v], mLow[nv.to]);

        is_articulation |= ~pv && mOrd[v] <= mLow[nv.to];
        if (mOrd[v] < mLow[nv.to]) mBridges.emplace_back(minmax(v, nv.to));
      } else if (nv.to != pv) { // 後退辺だったら
        mLow[v] = min(mLow[v], mOrd[nv.to]);
      }
    }
    is_articulation |= pv == -1 && cnt > 1;
    if (is_articulation) mArticulationPoints.push_back(v);

    return k;
  }

  void Init() {
    int k = 0;
    for (int i = 0; i < mGraph.size(); ++i) {
      if (!mUsed[i]) k = dfs(i, -1, k);
    }
  }

  vector<pair<int, int>> GetBridges() { return mBridges; }
  vector<int> GetArticulationPoints() { return mArticulationPoints; }

private:
  Graph mGraph;
  vector<int> mOrd;
  vector<int> mLow;
  vector<bool> mUsed;
  vector<pair<int, int>> mBridges;
  vector<int> mArticulationPoints;
};

int main() {
  int n, s, t;
  cin >> n;
  LowLink lowlink(n);
  vector<pair<int, int>> es;
  for (int i = 0; i < n; ++i) {
    cin >> s >> t;
    --s;
    --t;
    es.emplace_back(s, t);
    lowlink.add_edge(s, t);
  }
  lowlink.Init();
  auto ans = lowlink.GetBridges();
  map<pair<int, int>, bool> mp;
  for (auto p : ans) {
    mp[p] = true;
    mp[{p.second, p.first}] = true;
  }

  cout << n - ans.size() << '\n';
  for (int i = 0; i < n; ++i)
    if (!mp[es[i]]) cout << i + 1 << " \n"[i == n - 1];
  return 0;
}