#include<bits/stdc++.h>
using namespace std;
#define ALL(x) begin(x),end(x)
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define mod 1000000007
using ll=long long;
const int INF=1000000000;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

struct IOSetup{
    IOSetup(){
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(12);
    }
} iosetup;
 
template<typename T>
ostream &operator<<(ostream &os,const vector<T>&v){
    for(int i=0;i<(int)v.size();i++) os<<v[i]<<(i+1==(int)v.size()?"":" ");
    return os;
}
template<typename T>
istream &operator>>(istream &is,vector<T>&v){
    for(T &x:v)is>>x;
    return is;
}

struct LowLink{
    const vector<vector<int>> &g;
    vector<int> used,ord,low;
    vector<int> articulation;// 関節点
    vector<pair<int,int>> bridge;// 橋
    LowLink(const vector<vector<int>> &g):g(g){}
    int dfs(int pre,int now,int k){
        used[now]=1;
        ord[now]=k++;
        low[now]=ord[now];
        bool is_articulation=false,multi_edge=false;
        int cnt=0;
        for(auto &to:g[now]){
            if(to==pre and !multi_edge){
                multi_edge=true;
                continue;
            }
            if(!used[to]){
                cnt++;
                k=dfs(now,to,k);
                low[now]=min(low[now],low[to]);
                is_articulation|=(pre>=0 and low[to]>=ord[now]);
                if(ord[now]<low[to]) bridge.push_back(minmax(now,to));
            }else{
                // 後退辺
                low[now]=min(low[now],ord[to]);
            }
        }
        // 根の場合子が2個以上いれば関節点
        is_articulation|=(pre==-1 and cnt>1);
        if(is_articulation) articulation.push_back(now);
        return k;
    }
    void build(){
        used.assign(g.size(),0);
        ord.assign(g.size(),0);
        low.assign(g.size(),0);
        int k=0;
        for(int i=0;i<(int)g.size();i++)if(!used[i]) k=dfs(-1,i,k);
    }
    bool isBridge(int u,int v){
        if(ord[u]>ord[v]) swap(u,v);
        return ord[u]<low[v];
    }
};

using P=pair<int,int>;

signed main(){
    int n;cin>>n;
    vector<P> es;
    vector<vector<int>> g(n);
    rep(i,n){
        int u,v;cin>>u>>v;u--,v--;
        es.emplace_back(u,v);
        g[u].push_back(v);
        g[v].push_back(u);
    }

    LowLink link(g);
    link.build();
    vector<int> res;
    rep(i,n){
        auto [u,v]=es[i];
        if(!link.isBridge(u,v)) res.push_back(i+1);
    }
    cout<<res.size()<<endl;
    cout<<res<<endl;
    return 0;
}