//@formatter:off
#include<bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < int(n); ++i)
#define rrep(i,n) for (int i = int(n)-1; i >= 0; i--)
#define rep2(i,s,n) for (int i = int(s); i < int(n); ++i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define vvi vector<vector<int>>
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vd vector<double>
#define vvd vector<vector<double>>
#define vs vector<string>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define vvb vector<vector<bool>>
#define vp vector<P>
#define vvp vector<vector<P>>
using namespace std;
using ll = long long;
using P = pair<int,int>;
using LP = pair<ll,ll>;
template<class S,class T> istream& operator>>(istream &is,pair<S,T> &p) { return is >> p.first >> p.second; }
template<class S,class T> ostream& operator<<(ostream &os,const pair<S,T> &p) { return os<<'{'<<p.first<<","<<p.second<<'}'; }
template<class T> istream& operator>>(istream &is,vector<T> &v) { for(T &t:v){is>>t;} return is; }
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) { os<<'[';rep(i,v.size())os<<v[i]<<(i==int(v.size()-1)?"":","); return os<<']'; }
void Yes(bool b) { cout << (b ? "Yes" : "No") << '\n'; }
void YES(bool b) { cout << (b ? "YES" : "NO") << '\n'; }
template<class T> bool chmin(T& a,T b) {if(a > b){a = b; return true;} return false;}
template<class T> bool chmax(T& a,T b) {if(a < b){a = b; return true;} return false;}
const int inf = 1001001001;
const ll linf = 1001001001001001001;
//@formatter:on

class lowlink {
    vvi G;
    vi ord, low;
    
    int dfs(int v, int p, int k) {
        ord[v] = low[v] = k++;
        bool flag = false;
        int cnt = 0;
        for (int u : G[v]) {
            if (ord[u] < 0) {
                cnt++;
                k = dfs(u, v, k);
                chmin(low[v], low[u]);
                flag |= p >= 0 and ord[v] <= low[u];
                if (ord[v] < low[u]) bridge.eb(v, u);
            } else if (u != p) {
                chmin(low[v], ord[u]);
            }
        }
        flag |= p < 0 and cnt > 1;
        if (flag) articulation.pb(v);
        return k;
    }
    
    void init() {
        ord.assign(G.size(), -1);
        low.assign(G.size(), -1);
        int k = 0;
        rep(i, G.size()) {
            if (ord[i] < 0) k = dfs(i, -1, k);
        }
    }

public:
    vi articulation;
    vp bridge;
    
    lowlink(vvi &G) : G(G) { init(); }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n;
    cin >> n;
    vvi G(n);
    map<P, int> mp;
    rep(i, n) {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        mp[{a, b}] = i+1;
        G[a].pb(b);
        G[b].pb(a);
    }
    lowlink lk(G);
    for (auto p : lk.bridge) {
        if (mp.count(p)) mp.erase(p);
        swap(p.first, p.second);
        if (mp.count(p)) mp.erase(p);
    }
    cout << mp.size() << '\n';
    for (auto p : mp) {
        cout << p.second << ' ';
    }
    cout << endl;
}