#include <iostream>
#include <vector>
#include <queue>

void solve() {
    int n;
    std::cin >> n;

    std::vector<std::pair<int, int>> es(n);
    std::vector<std::vector<int>> graph(n);
    for (auto& [u, v] : es) {
        std::cin >> u >> v;
        --u, --v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    std::queue<int> que;
    std::vector<int> deg(n, 0);
    for (int v = 0; v < n; ++v) {
        deg[v] = graph[v].size();
        if (deg[v] == 1) que.push(v);
    }

    std::vector<bool> broken(n, false);
    while (!que.empty()) {
        int v = que.front();
        que.pop();

        broken[v] = true;
        for (auto u : graph[v]) {
            if (--deg[u] == 1) que.push(u);
        }
    }

    std::vector<int> ans;
    for (int i = 0; i < n; ++i) {
        auto [u, v] = es[i];
        if (!broken[u] && !broken[v]) ans.push_back(i);
    }

    std::cout << ans.size() << "\n";
    for (auto i : ans) std::cout << i + 1 << " ";
    std::cout << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}