#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ALL(x) (x).begin(), (x).end()
#ifdef LOCAL
#include "debug.hpp"
#else
#define debug(...) void(0)
#endif

template <typename T> istream& operator>>(istream& is, vector<T>& v) {
    for (T& x : v) is >> x;
    return is;
}
template <typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
    for (size_t i = 0; i < v.size(); i++) {
        os << v[i] << (i + 1 == v.size() ? "" : " ");
    }
    return os;
}

template <typename T> T gcd(T x, T y) { return y != 0 ? gcd(y, x % y) : x; }
template <typename T> T lcm(T x, T y) { return x / gcd(x, y) * y; }

int topbit(signed t) { return t == 0 ? -1 : 31 - __builtin_clz(t); }
int topbit(long long t) { return t == 0 ? -1 : 63 - __builtin_clzll(t); }
int botbit(signed a) { return a == 0 ? 32 : __builtin_ctz(a); }
int botbit(long long a) { return a == 0 ? 64 : __builtin_ctzll(a); }
int popcount(signed t) { return __builtin_popcount(t); }
int popcount(long long t) { return __builtin_popcountll(t); }
bool ispow2(int i) { return i && (i & -i) == i; }
long long MSK(int n) { return (1LL << n) - 1; }

template <class T> T ceil(T x, T y) {
    assert(y >= 1);
    return (x > 0 ? (x + y - 1) / y : x / y);
}
template <class T> T floor(T x, T y) {
    assert(y >= 1);
    return (x > 0 ? x / y : (x - y + 1) / y);
}

template <class T1, class T2> inline bool chmin(T1& a, T2 b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T1, class T2> inline bool chmax(T1& a, T2 b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T> void mkuni(vector<T>& v) {
    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
}
template <typename T> int lwb(const vector<T>& v, const T& x) { return lower_bound(v.begin(), v.end(), x) - v.begin(); }

const int INF = (1 << 30) - 1;
const long long IINF = (1LL << 60) - 1;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const int MOD = 998244353;
// const int MOD = 1000000007;

void solve() {
    int n;
    cin >> n;
    vector<vector<int>> G(n);
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        G[a].emplace_back(b);
        G[b].emplace_back(a);
    }

    vector<int> sub(n, 1);
    auto dfs = [&](auto self, int v, int p) -> set<int> {
        set<int> s;
        bool first = true;
        for (int& u : G[v]) {
            if (u == p) continue;
            auto ch = self(self, u, v);
            sub[v] += sub[u];
            if (first) {
                swap(s, ch);
                first = false;
                continue;
            }
            if (s.size() > ch.size()) swap(s, ch);
            set<int> ns;
            for (int x : s) {
                if (ch.count(x)) {
                    ns.emplace(x);
                }
            }
            swap(s, ns);
        }
        s.emplace(sub[v]);
        return s;
    };

    auto res = dfs(dfs, 0, -1);
    vector<int> ans;
    for (int x : res) ans.emplace_back(x);
    cout << ans.size() << '\n';
    cout << ans << '\n';
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int z;
    cin >> z;
    for (; z--;) solve();
    return 0;
}