#include<bits/stdc++.h>
#define LL long long
#define LLL __int128
#define uint unsigned
#define ldb long double
#define uLL unsigned long long
using namespace std;
const int N=105;
int n;
int deg[N];
vector<int>G[N];
vector<vector<int>>ans;
inline void dfs(int u,int fa){
    for(auto v:G[u])if(v!=fa)dfs(v,u);
    ans.back().emplace_back(u);
}
inline void MAIN(){
    cin>>n,ans.clear();
    for(int i=1;i<=n;++i)G[i].clear();
    for(int i=1;i<n;++i){
        int u,v;cin>>u>>v;
        G[u].emplace_back(v);
        G[v].emplace_back(u);
    }
    if(n<3)return cout<<"0\n",void();
    for(int i=1;i<=n;++i)
        if(G[i].size()==n-1){
            cout<<"2\n";
            for(int j:G[i])cout<<j<<' ';cout<<i<<'\n';
            reverse(G[i].begin(),G[i].end());
            for(int j:G[i])cout<<j<<' ';cout<<i<<'\n';
            return;
        }
        else deg[i]=G[i].size();
    for(int i=1;i<=n;++i)if(G[i].size()==1)--deg[G[i][0]],deg[i]=0;
    for(int i=1;i<=n;++i)if(deg[i]==1){
        ans.emplace_back(),dfs(i,0);
        if(ans.size()==1)for(int j=1;j<=n;++j)reverse(G[j].begin(),G[j].end());
    }
    cout<<ans.size()<<'\n';
    for(auto vec:ans){
        for(int i:vec)cout<<i<<' ';
        cout<<'\n';
    }
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    int t=1;cin>>t;while(t--)MAIN();
    return 0;
}
/*
2
5
2 3
3 1
5 1
5 4
5
1 4
2 3
3 1
5 3
*/