#include <bits/stdc++.h>

using namespace std;
void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}
int main() {
    fast_io();
    int n;
    cin >> n;
    vector<set<int>> g(n);
    map<pair<int, int>, int> edge_id;
    for (int i = 0; i < n; i++) {
        int u, v;
        cin >> u >> v;
        u--, v--;
        g[u].insert(v);
        g[v].insert(u);
        edge_id[{u, v}] = edge_id[{v, u}] = i + 1;
    }
    deque<int> q;
    for (int i = 0; i < n; i++) {
        if (g[i].size() == 1) {
            q.push_back(i);
        }
    }
    while (!q.empty()) {
        int u = q.front();
        q.pop_front();
        for (int v : g[u]) {
            g[v].erase(u);
            if (g[v].size() == 1) {
                q.push_back(v);
            }
        }
        g[u].clear();
    }
    vector<int> ans;
    for (int i = 0; i < n; i++) {
        for (int v : g[i]) {
            ans.push_back(edge_id[{i, v}]);
        }
    }
    sort(ans.begin(), ans.end());
    ans.erase(unique(ans.begin(), ans.end()), ans.end());
    cout << ans.size() << "\n";
    for (int i = 0; i < ans.size(); i++) {
        cout << ans[i] << " ";
    }
    cout << endl;
}