#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}

std::vector<std::vector<int> > hen;
std::vector<bool> used;
std::vector<bool> inloop;

std::vector<int> parent;
std::vector<int> depth;

void climb(int i, int j) {
	if (depth[i] < depth[j]) std::swap(i, j);
	while (depth[i] > depth[j]) inloop[i] = true, i = parent[i];
	while (i != j) inloop[i] = inloop[j] = true, i = parent[i], j = parent[j];
	if (i != -1) inloop[i] = true;
}

void dfs(int i, int prev) {
	used[i] = true;
	parent[i] = prev;
	for (auto j : hen[i]) {
		if (!used[j]) depth[j] = depth[i] + 1, dfs(j, i);
		else if (j != prev) climb(i, j);
	}
}

int main() {
	int n = ri();
	hen.resize(n);
	int a[n], b[n];
	for (int i = 0; i < n; i++) {
		a[i] = ri() - 1;
		b[i] = ri() - 1;
		hen[a[i]].push_back(b[i]);
		hen[b[i]].push_back(a[i]);
	}
	used.resize(n);
	inloop.resize(n);
	parent.resize(n);
	depth.resize(n);
	dfs(0, -1);
	
	/*
	for (int i = 0; i < n; i++) if (inloop[i]) std::cerr << i << " ";
	std::cerr << std::endl;*/
	
	std::vector<int> res;
	for (int i = 0; i < n; i++) if (inloop[a[i]] && inloop[b[i]]) res.push_back(i);
	printf("%d\n", (int) res.size());
	for (int i = 0; i < (int) res.size(); i++) {
		if (i) printf(" ");
		printf("%d", res[i] + 1);
	}
	puts("");
	return 0;
}