#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
// constexpr int mod = 1000000007;
constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

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

    int N;
    cin >> N;
    vector<int> a(N), b(N);
    vector<vector<int>> graph(N);
    for(int i = 0; i < N; ++i){
        cin >> a[i] >> b[i];
        --a[i], --b[i];
        graph[a[i]].emplace_back(b[i]);
        graph[b[i]].emplace_back(a[i]);
    }
    vector<int> ans;
    for(int i = 0; i < N; ++i){
        if(graph[a[i]].size() == 1 || graph[b[i]].size() == 1)  continue;
        ans.emplace_back(i + 1);
    }
    int n = ans.size();
    cout << n << '\n';
    for(int i = 0; i < n; ++i){
        cout << ans[i];
        cout << ((i == n - 1) ? '\n' : ' ');
    }

    return 0;
}