#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

int n;
vector<int> g[100000];
map<pair<int, int>, int> id;
int ord[100000];
int low[100000];
int used[100000];
set<int> bs;

// lowlink algorithm
void dfs(int v, int &k, int par = -1) {
  ord[v] = k++;
  low[v] = ord[v];
  used[v] = true;
  
  for (int w: g[v]) {
    if (w == par) continue;
    if (!used[w]) {
      dfs(w, k, v);
      low[v] = min(low[v], low[w]);
      if (ord[v] < low[w])
        bs.insert(id[make_pair(min(v, w), max(v, w))]);
    } else {
      low[v] = min(low[v], ord[w]);
    }
  }
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  cin >> n;
  for (int i = 1; i <= n; i++) {
    int a, b;
    cin >> a >> b;
    --a, --b;
    g[a].push_back(b);
    g[b].push_back(a);
    id[make_pair(min(a, b), max(a, b))] = i;
  }

  int k = 0;
  dfs(0, k);

  vector<int> ret;
  for (int i = 1; i <= n; i++)
    if (!bs.count(i))
      ret.push_back(i);

  cout << ret.size() << endl;
  for (int x: ret)
    cout << x << " ";
  cout << endl;
  
  return 0;
}