#include <bits/stdc++.h>

using namespace std;
using ll = long long;

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

    int N, A, B;
    cin >> N;
    vector<vector<pair<int, int>>> E(N);

    for (int i=0; i<N; i++){
        cin >> A >> B;
        A--; B--;
        E[A].push_back({B, i});
        E[B].push_back({A, i});
    }

    vector<int> in(N, -1), low(N), tour, ancestor(N);
    vector<bool> double_edge(N);
    auto lowlink=[&](auto self, int from, int p)->void{
        in[from] = tour.size();
        low[from] = tour.size();
        tour.push_back(from);
        ancestor[from] = p;
        for (auto [to, _] : E[from]){
            if (to == p){
                if (double_edge[from]) low[from] = min(low[from], in[to]);
                else double_edge[from]=1;
                continue;
            }
            if (in[to] != -1){
                if (in[to] > in[from]) continue;
                low[from] = min(low[from], in[to]); //後退辺(子孫->祖先)を遡る
            }
            else self(self, to, from);
        }
    };
    lowlink(lowlink, 0, -1);
    for (int i=N-1; i>=0; i--){
        int x = tour[i];
        for (auto [y, _] : E[x]){
            if (y == ancestor[x]) continue;
            low[x] = min(low[x], low[y]);
        }
    }

    //二重辺連結成分分解(two edge connected component)
    vector<vector<int>> tecc_groups;
    vector<int> _tecc, bridge, roots={0};
    vector<int> tecc_idx(N, -1); //頂点iの含まれる成分の番号
    auto tecc=[&](auto self, int from)->void{
        _tecc.push_back(from);
        tecc_idx[from] = tecc_groups.size();
        for (auto [to, idx] : E[from]){
            if (tecc_idx[to] != -1) continue;
            if (low[to] > in[from]){
                bridge.push_back(idx);
                roots.push_back(to);
            }
            else self(self, to);
        }
    };
    while(!roots.empty()){
        int root = roots.back();
        roots.pop_back();
        tecc(tecc, root);
        tecc_groups.push_back(_tecc);
        _tecc.clear();
    }

    vector<bool> ok(N, 1);
    for (auto x : bridge) ok[x] = 0;
    cout << N-bridge.size() << endl;
    for (int i=0; i<N; i++) if (ok[i]) cout << i+1 << " ";
    cout << endl;

    return 0;
}