/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.10.10 01:43:59
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;


struct LowLink {
private:
    vector< vector< int > > G;
    int V; 
    vector< int > used, ord, low;
    int dfs(int idx, int k, int par) {
        used[idx] = true;
        ord[idx] = k++;
        low[idx] = ord[idx];
        bool is_articulation = false;
        int cnt = 0;
        for (auto &to : G[idx]) {
            if (!used[to]) {
                ++cnt;
                k = dfs(to, k, idx);
                low[idx] = min(low[idx], low[to]);
                is_articulation |= ~par && low[to] >= ord[idx];
                if (ord[idx] < low[to]) bridge.push_back(minmax(idx, (int)to));
            }
            else if (to != par) {
                low[idx] = min(low[idx], ord[to]);
            }
        }
        is_articulation |= par == -1 && cnt > 1;
        if (is_articulation) articulation.push_back(idx);
        return k;
    }
public:
    vector< int > articulation; 
    vector< pair< int, int > > bridge; 
    LowLink(int V) : V(V) {
        G.resize(V);
    }
    
    void add_edge(int v, int u) {
        G[v].push_back(u);
        G[u].push_back(v);
    }
    void build() {
        used.assign(V, 0);
        ord.assign(V, 0);
        low.assign(V, 0);
        int k = 0;
        for (int i = 0; i < V; i++) {
            if (!used[i]) k = dfs(i, k, -1);
        }
    }
};
int main() {
    int n;cin >> n;
    LowLink g(n);
    vector<pair<int,int>> edge(n);
    map<pair<int,int>,int> mp;
    for (int i = 0; i < n; i++) {
        int a,b;cin >> a >> b;
        a--;b--;
        edge[i] = {a,b};
        mp[{a,b}] = i+1;
        g.add_edge(a,b);
    }
    g.build();
    cout << n - g.bridge.size() << endl;
    for (auto p : g.bridge) {
        mp[p] = -1;
    }
    for (int i = 0; i < n; i++) {
        if (mp[edge[i]] != -1) cout << i+1 << " ";
    }
    cout << endl;
    return 0;
}