#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;
template<class T> void chmin(T &a,const T &b){if(a>b) a=b;}
template<class T> void chmax(T &a,const T &b){if(a<b) a=b;}

struct Edge{
    int from,to;
    ll cost;
    int id;
    Edge(){}
    Edge(int from,int to,ll cost=1,int id=0):from(from),to(to),cost(cost),id(id){}
};

struct LowLink{
    int N;
    vector<vector<Edge>> g;

    vector<int> ord,low,vis;
    vector<int> articulations;
    vector<Edge> bridges;

    LowLink(int N,vector<vector<Edge>> &g):N(N),g(g),ord(N),low(N),vis(N){}

    void dfs(int now,int par,int &cnt){
        ord[now]=cnt++;
        vis[now]=1;
        bool isArt=false;
        int num=0;
        low[now]=ord[now];
        for(auto e:g[now]){
            if(e.to==par) continue;

            if(vis[e.to]){
                chmin(low[now],ord[e.to]);
            }else{
                num++;
                dfs(e.to,now,cnt);
                chmin(low[now],low[e.to]);
                if(ord[now]<low[e.to]) bridges.emplace_back(e);
                if(ord[now]<=low[e.to]) isArt=true;
            }
        }
        if(par==-1&&num>1) articulations.push_back(now);
        if(par!=-1&&isArt) articulations.push_back(now);  
    }

    void build(){
        int cnt=0;
        for(int i=0;i<N;i++) if(vis[i]==0) dfs(i,-1,cnt);
    }
};


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

  int N;
  cin>>N;
  vector<vector<Edge>> g(N);
  rep(i,N){
      int a,b;
      cin>>a>>b;
      a--;b--;
      g[a].emplace_back(Edge{a,b,1,i});
      g[b].emplace_back(Edge{b,a,1,i});
  }
  LowLink LL(N,g);
  LL.build();

  vector<Edge> bridges=LL.bridges;
  vector<int> used(N,0);
  for(auto e:bridges) used[e.id]=1;

  vector<int> ans;
  rep(i,N) if(used[i]==0) ans.push_back(i);
  
  cout<<ans.size()<<endl;
  rep(i,ans.size()) cout<<ans[i]+1<<" ";
  cout<<endl;

  return 0;
}