#include <iostream>
#include <vector>
#include <queue>
#define rep(i, n) for(i = 0; i < n; i++)
using namespace std;

int n;
vector<int> et[100000];
int a[100000], b[100000];
int inV[100000];

int main() {
	int i;
	
	cin >> n;
	rep(i, n) {
		cin >> a[i] >> b[i];
		a[i]--; b[i]--;
		et[a[i]].push_back(b[i]);
		et[b[i]].push_back(a[i]);
		inV[a[i]]++;
		inV[b[i]]++;
	}
	
	queue<int> que;
	rep(i, n) {
		if (inV[i] == 1) {
			que.push(i);
		}
	}
	
	while (!que.empty()) {
		int v = que.front(); que.pop();
		for (int nv : et[v]) {
			inV[nv]--;
			if (inV[nv] == 1) {
				que.push(nv);
			}
		}
	}
	
	vector<int> ans;
	rep(i, n) {
		if (inV[a[i]] >= 2 && inV[b[i]] >= 2) {
			ans.push_back(i);
		}
	}
	
	cout << ans.size() << endl;
	rep(i, ans.size()) {
		cout << ans[i] + 1;
		if (i + 1 < ans.size()) cout << " ";
	}
	cout << endl;
	
	return 0;
}