#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N;
	cin >> N;
	vector<vector<int>> g(N);
	vector<int> A(N), B(N);
	REP(i, N) {
		scanf("%d %d", &A[i], &B[i]);
		--A[i]; --B[i];
		g[A[i]].emplace_back(B[i]);
		g[B[i]].emplace_back(A[i]);
	}
	
	vector<int> ord(N, -1), low(N);
	auto dfs = [&](auto self, int u, int par, int & num) -> int {
		ord[u] = low[u] = num++;
		for (int v : g[u]) {
			if (v == par) continue;
			if (ord[v] == -1) {
				ord[v] = ord[u] + 1;
				chmin(low[u], self(self, v, u, num));
			}
			else chmin(low[u], ord[v]);
		}
		return low[u];
	};
	int num = 0;
	dfs(dfs, 0, -1, num);
	
	vector<int> ans;
	REP(i, N) {
		if (ord[A[i]] > ord[B[i]]) swap(A[i], B[i]);
		if (ord[A[i]] >= low[B[i]]) ans.emplace_back(i);
	}
	
	cout << ans.size() << endl;
	REP(i, ans.size()) printf("%d%c", ans[i] + 1, " \n"[i + 1 == ans.size()]);
}