#include <bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//#include<boost/multiprecision/cpp_dec_float.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
#define fi first
#define se second
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll mod_998244353 = 998244353;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

//using lll=boost::multiprecision::cpp_int;
//using Double=boost::multiprecision::number<boost::multiprecision::cpp_dec_float<1024>>;//仮数部が1024桁
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

template <typename T>
T mypow(T x, T n, const T &p = -1)
{ //x^nをmodで割った余り

	if (p != -1)
	{
		x %= p;
	}
	T ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;


template<typename T>
struct LowLink{
	vector<vector<T>> g;
	vector<int>ord,low;
	vector<int>articulation;//関節点
	vector<pair<int,int>>bridge;//橋
	LowLink(const vector<vector<T>> &_g):g(_g){
		ord.assign(g.size(),-1);
		low.assign(g.size(),0);
	}
	void dfs(int v=0,int par=-1,int cnt=0){
		ord[v]=cnt++;
		low[v]=ord[v];
		bool is_arp=false;
		for(auto x:g[v]){
			if(ord[x]==-1){
				dfs(x,v,cnt);
				low[v]=min(low[v],low[x]);
				if(ord[v]<low[x]){
					int from=min(v,x);
					int to=max(v,x);
					bridge.emplace_back(from,to);
				}
				if(ord[v]<=low[x]){
					is_arp=true;
				}
			}else if(x!=par){//x=parを許容すると橋のときに壊れる
				low[v]=min(ord[x],low[v]);
			}
		}
		if(is_arp){
			articulation.emplace_back(v);
		}
	}
	void build(){
		dfs();
	}
};
using P=pair<int,int>;
void solve()
{	
	int n;
	cin>>n;
	vector<vector<int>>g(n);
	map<pair<int,int>,int>mp;
	rep(i,n){
		int a,b;
		cin>>a>>b;
		a--;b--;
		g[a].eb(b);
		g[b].eb(a);
		if(a>b)swap(a,b);
		mp[P{a,b}]=i+1;
	}
	LowLink<int>lowlink(g);
	lowlink.build();
	for(auto e:lowlink.bridge){
		if(e.first>e.second)swap(e.fi,e.se);
		mp.erase(P(e.first,e.second));
	}
	int ans=mp.size();
	cout<<ans<<"\n";
	for(auto itr=mp.begin();itr!=mp.end();++itr){
		if(itr!=mp.begin())cout<<" ";
		cout<<itr->second;
	}
	cout<<"\n";
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}