#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#define llint long long
#define inf 1e18
#define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++)
#define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define mod 1000000007

using namespace std;
typedef pair<llint, llint> P;

llint n;
map<P, llint> mp;
bool used[100005];

vector<int> G[100005];
vector<P> bridge;
int pre[100005], low[100005];

int id = 1;
int bridge_dfs(int v, int prev)
{
	pre[v] = id++;
	int ret = pre[v];
	for(int i = 0; i < G[v].size(); i++){
		if(G[v][i] == prev) continue;
		if(pre[G[v][i]]) ret = min(ret, pre[G[v][i]]);
		else ret = min(ret, bridge_dfs(G[v][i], v));
	}
	return low[v] = ret;
}

//find the unordered pairs{start, end} of all bridges.
void findBridge(int v = 1)
{
	bridge_dfs(v, -1);
	for(int i = 1; i <= n; i++){
		for(int j = 0; j < G[i].size(); j++){
			if(pre[i] < pre[G[i][j]] && low[G[i][j]] > pre[i]) bridge.push_back(make_pair(i, G[i][j]));
		}
	}
}

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n;
	llint u, v;
	for(int i = 1; i <= n; i++){
		cin >> u >> v;
		if(u > v) swap(u, v);
		mp[P(u, v)] = i;
		G[u].push_back(v);
		G[v].push_back(u);
	}
	
	findBridge();
	
	vector<llint> ans;
	for(int i = 0; i < bridge.size(); i++){
		u = bridge[i].first, v = bridge[i].second;
		if(u > v) swap(u, v);
		used[mp[P(u, v)]] = true;
	}
	for(int i = 1; i <= n; i++) if(!used[i]) ans.push_back(i);
	
	cout << ans.size() << endl;
	for(int i = 0; i < ans.size(); i++) cout << ans[i] << " "; cout << endl;
	
	return 0;
}