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

using ll = long long;
using ld = long double;
#define pb push_back
#define oo 1000000000000000LL
#define ff first
#define ss second
const int mx=1000001;
vector<int> g[mx];
int used[mx],n,sub[mx],out[mx],leaf[mx];
void dfs(int u) {
    used[u]=1;
    sub[u]=1;
    for(int i=0;i<int(g[u].size());++i) {
        int v=g[u][i];
        if(!used[v]) {
            dfs(v);
            sub[u]+=sub[v];
            leaf[u]+=leaf[v];
        }
    }
}
int main(){
    ios::sync_with_stdio(false); cin.tie(0);
    int t; cin>>t;
    while(t--) {
        cin >> n;
        int k=0;
        for(int i=0;i<=n;++i) {
            sub[i]=used[i]=leaf[i]=out[i]=0;
            g[i].clear();
        }
        for(int i=1;i<n;++i) {
            int u,v; cin>>u>>v;
            g[u].pb(v),g[v].pb(u);
            out[u]++;
        }
        for(int i=1;i<=n;++i) {
            if(!out[i]) {
                leaf[i]=1; ++k;
            }
        }
        dfs(1);
        vector<int>ans;
        int check[n+2];
        memset(check,0,sizeof(check));
        for(int i=1;i<=n;++i) {
            check[sub[i]]+=leaf[i];
        }
        for(int i=1;i<=n;++i) {
            if(check[i]==k) {
                ans.pb(i);
            }
        }
        cout << int(ans.size()) << "\n";
        for(int i=0;i<int(ans.size());++i) {
            cout << ans[i] << " ";
        }
        cout << "\n";
    }
    return 0;
}