#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define endl '\n'
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))

using namespace std;

const ll INF=1e6+1;

vector<vector<ll>> to;
vector<ll> visited,loop;

ll num=-1;

void dfs1(ll v,ll p=-1){
    if(visited[v]){
        num=v;
        return;
    }
    visited[v]=1;
    for(auto x:to[v]){
        dfs1(x,v);
    }
    return ;
}
set<ll> ans;
map<pll,ll> m;

bool dfs(ll v,ll p=-1){
    if(visited[v]){
        if(m.count({v,p})){
            ans.insert(m[{v,p}]);
        }
        if(m.count({p,v})){
            ans.insert(m[{p,v}]);
        }
        return true;
    }
    visited[v]=1;
    for(auto x:to[v]){
        if(x==p) continue;
        if(dfs(x,v)){
            if(m.count({v,p})){
                ans.insert(m[{v,p}]);
            }
            if(m.count({p,v})){
                ans.insert(m[{p,v}]);
            }
            return true;
        }
    }
    return false;
}


int main(){
    ll n;
    cin >> n ;
    vector<ll> a(n),b(n);
    to=vector<vector<ll>>(n);
    visited=vector<ll>(n);
    
    rep(i,n){
        cin >> a[i] >> b[i];
        a[i]--;
        b[i]--;
        to[a[i]].push_back(b[i]);
        to[b[i]].push_back(a[i]);
        m[{a[i],b[i]}]=i;
    }
    dfs1(0LL);
    visited=vector<ll>(n);
    dfs(num);
    cout << ans.size() << endl;
    ll i=0;
    for(auto x:ans){
        if(i) cout << " ";
        cout << x+1;
        i++;
    }
    cout << endl;
    return 0;
}