#include <bits/stdc++.h>

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

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

void dfs(int i, int prev) {
	used[i] = 1;
	stack.push_back(i);
	for (auto j : hen[i]) {
		if (!used[j]) dfs(j, i);
		else if (used[j] == 1 && j != prev) {
			for (int k = stack.size(); k--; ) {
				inloop[stack[k]] = true;
				if (stack[k] == j) break;
			}
		}
	}
	used[i] = 2;
	stack.pop_back();
}

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);
	dfs(0, -1);
	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;
}