#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i, n) for (int i = 0; i < (int) (n); i++)
#define reps(i, n) for (int i = 1; i <= (int) (n); i++)
#define all(a) (a).begin(), (a).end()
#define uniq(a) (a).erase(unique(all(a)), (a).end())
#define bit(n) (1LL << (n))
#define dump(a) cerr << #a " = " << (a) << endl
using vint = vector<int>;
using pint = pair<int, int>;
using vpint = vector<pint>;
template<typename T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
constexpr double PI = 3.1415926535897932384626433832795028;
constexpr int DY[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0};
constexpr int DX[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
int sign(int a) { return (a > 0) - (a < 0); }
int cdiv(int a, int b) { return (a - 1 + b) / b; }
template<typename T> void fin(T a) {
    cout << a << endl;
    exit(0);
}
template<typename T> T sq(T a) { return a * a; }
template<typename T, typename U> bool chmax(T &a, const U &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> bool chmin(T &a, const U &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> ostream &operator<<(ostream &os, const pair<T, U> &a) {
    os << "(" << a.first << ", " << a.second << ")";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const vector<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) {
        os << *itr << (next(itr) != a.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const deque<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) {
        os << *itr << (next(itr) != a.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const set<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) {
        os << *itr << (next(itr) != a.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) {
        os << *itr << (next(itr) != a.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T, typename U> ostream &operator<<(ostream &os, const map<T, U> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) {
        os << *itr << (next(itr) != a.end() ? ", " : "");
    }
    os << "}";
    return os;
}
struct setup {
    static constexpr int PREC = 20;
    setup() {
        cout << fixed << setprecision(PREC);
        cerr << fixed << setprecision(PREC);
    };
} setup;

struct low_link {
    int n;
    std::vector<int> ord, low, articulations;
    std::vector<std::vector<int>> adj;
    std::vector<std::pair<int, int>> bridges;
    low_link(const std::vector<std::vector<int>> &adj) : n(adj.size()), adj(adj), ord(n), low(n) {
        std::vector<bool> visited(n);
        int k = 0;
        auto dfs = [&](auto &&self, int cur, int par) -> void {
            visited[cur] = true;
            ord[cur] = k++;
            low[cur] = ord[cur];
            int cnt = 0;
            bool is_articulation = false;
            for (int to : adj[cur]) {
                if (!visited[to]) {
                    cnt++;
                    self(self, to, cur);
                    low[cur] = std::min(low[cur], low[to]);
                    is_articulation |= ord[cur] <= low[to];
                    if (ord[cur] < low[to]) { bridges.emplace_back(std::minmax(cur, to)); }
                } else if (to != par) { low[cur] = std::min(low[cur], ord[to]); }
            }
            if (par == -1) { is_articulation = cnt >= 2; }
            if (is_articulation) { articulations.emplace_back(cur); }
        };
        dfs(dfs, 0, -1);
    }
};

signed main() {
    int N;
    cin >> N;
    vint a(N), b(N);
    vector<vint> adj(N);
    map<pint, int> idx;
    rep(i, N) {
        cin >> a[i] >> b[i], a[i]--, b[i]--;
        idx[{a[i], b[i]}] = i;
        adj[a[i]].emplace_back(b[i]);
        adj[b[i]].emplace_back(a[i]);
    }
    low_link ll(adj);
    cout << N - ll.bridges.size() << endl;
    vint ans(N, 1);
    for (pint p:ll.bridges) { ans[idx[p]] = 0; }
    rep(i, N) {
        if (ans[i]) { cout << i + 1 << " "; }
    }
    cout << endl;
}