#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int inf=1e9+7;
const int N=1000013;
vector<int>mp[N];
basic_string<int>s[N];

int v[N],sz[N];
void dfs(int x,int fa) {
    sz[x]=1;
    basic_string<int>v;
    for(auto i:mp[x])if(i^fa)dfs(i,x),sz[x]+=sz[i],v+=s[i];
    if(mp[x].size()>1+(x!=1)) {
        sort(v.begin(),v.end());
        for(int i=1,f=0;i<v.size();i++)if(!f&&v[i]==v[i-1])f=1,s[x]+=v[i];else if(v[i]!=v[i-1])f=0;
    }else swap(s[x],v);
    s[x]+=sz[x];
}

void solve(){
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)mp[i].clear(),v[i]=0,s[i].clear();
    for(int i=1,x,y;i<n;i++)cin>>x>>y,mp[x].push_back(y),mp[y].push_back(x);
    dfs(1,0);
    vector<int>b;
    cout<<s[1].size()<<'\n';
    for(auto x:s[1])cout<<x<<' ';cout<<'\n';
}

int main(){
    ios::sync_with_stdio(false);
    int T=1;
    cin>>T;
    while(T--)solve();
}