#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
// constexpr int mod = 1000000007;
constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

struct LowLink{
    using G = vector<vector<int>>;

    const G& g;
    vector<int> visited, order, low;
    vector<int> articulation;           // 関節点
    vector<pair<int, int>> bridge;      // 橋 (order[from] < low[to])
    int LinkSize = 0;       // 連結成分の個数

    LowLink(const G &g) : g(g) {}

    int dfs(int from, int k, int par = -1){
        visited[from] = true;
        order[from] = k++;
        low[from] = order[from];
        bool is_articulation = false;
        int cnt = 0;
        for(int to : g[from]){
            if(!visited[to]){
                ++cnt;
                k = dfs(to, k, from);
                low[from] = min(low[from], low[to]);
                // 頂点 from が DFS 木の根以外であるときの関節点となる条件
                is_articulation |= ~par && low[to] >= order[from];
                // (from, to) が条件を満たせば、橋に追加
                if(order[from] < low[to]) bridge.emplace_back(minmax(from, (int)to));
            }
            else if(to != par){
                low[from] = min(low[from], order[to]);
            }
        }
        // 頂点 from がDFS木の根であるときの関節点となる条件
        is_articulation |= par == -1 && cnt > 1;
        if(is_articulation) articulation.push_back(from);
        return k;
    }

    virtual void build(){
        visited.assign(g.size(), 0);
        order.assign(g.size(), 0);
        low.assign(g.size(), 0);
        int k = 0;
        for(int i = 0; i < g.size(); ++i){
            if(!visited[i]){
                k = dfs(i, k);
                ++LinkSize;
            }
        }
    }
};

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

    int N;
    cin >> N;
    vector<int> a(N), b(N);
    vector<vector<int>> graph(N);
    for(int i = 0; i < N; ++i){
        cin >> a[i] >> b[i];
        --a[i], --b[i];
        graph[a[i]].emplace_back(b[i]);
        graph[b[i]].emplace_back(a[i]);
    }

    LowLink g(graph);
    g.build();
    set<P> bridge;
    for(auto [u, v] : g.bridge){
        bridge.emplace(minmax(u, v));
    }

    vector<int> ans;
    for(int i = 0; i < N; ++i){
        if(bridge.find(minmax(a[i], b[i])) != bridge.end()) continue;
        ans.emplace_back(i + 1);
    }

    int n = ans.size();
    cout << n << '\n';
    for(int i = 0; i < n; ++i){
        cout << ans[i];
        cout << ((i == n - 1) ? '\n' : ' ');
    }

    return 0;
}