#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  vector<int> a(N), b(N);
  for (int i = 0; i < N; i++){
    cin >> a[i] >> b[i];
    a[i]--;
    b[i]--;
  }
  vector<vector<int>> E(N);
  for (int i = 0; i < N; i++){
    E[a[i]].push_back(b[i]);
    E[b[i]].push_back(a[i]);
  }
  vector<int> deg(N);
  for (int i = 0; i < N; i++){
    deg[i] = E[i].size();
  }
  queue<int> Q;
  for (int i = 0; i < N; i++){
    if (deg[i] == 1){
      Q.push(i);
    }
  }
  vector<bool> ok(N, true);
  while (!Q.empty()){
    int v = Q.front();
    Q.pop();
    ok[v] = false;
    for (int w : E[v]){
      deg[w]--;
      if (deg[w] == 1){
        Q.push(w);
      }
    }
  }
  vector<int> p;
  for (int i = 0; i < N; i++){
    if (ok[a[i]] && ok[b[i]]){
      p.push_back(i);
    }
  }
  int K = p.size();
  cout << K << endl;
  for (int i = 0; i < K; i++){
    cout << p[i] + 1;
    if (i < K - 1){
      cout << ' ';
    }
  }
  cout << endl;
}