#include <bits/stdc++.h>

using namespace std;

const int N = 105;

vector<int> G[N];
int deg[N], vis[N];

signed main() {
    int T; scanf("%d", &T);
    while (T--) {
        int n; scanf("%d", &n);
        for (int i = 1; i <= n; ++i) G[i].clear();
        for (int i = 1, x, y; i < n; ++i) {
            scanf("%d%d", &x, &y), G[x].push_back(y), G[y].push_back(x);
        }
        mt19937 rnd;
        vector<int> z;
        for (int i = 1; i <= n; ++i) {
            if (G[i].size() == 1) z.push_back(i);
        }
        z.pop_back();
        printf("%d\n", (int)z.size());
        for (auto x : z) {
            vector<int> val;
            memset(vis, 0, sizeof(vis));
            vis[x] = 1;
            vector<int> Q;
            Q.push_back(x);
            while (!Q.empty()) {
                int v = Q[rnd() % Q.size()]; Q.erase(find(Q.begin(), Q.end(), v));
                val.push_back(v);
                shuffle(G[v].begin(), G[v].end(), rnd);
                for (auto w : G[v]) if (!vis[w]++) Q.push_back(w);
            }
            reverse(val.begin(), val.end());
            for (int i = 0; i < n; ++i) printf("%d%c", val[i], " \n"[i + 1 == n]);
        }
    }
    return 0;
}