#include <bits/stdc++.h>

using namespace std;

const int N = 105;

vector<int> G[N];
int deg[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;
        printf("%d\n", n);
        for (int i = 1; i <= n; ++i) {
            vector<int> z, Q;
            for (int j = 1; j <= n; ++j) {
                deg[j] = G[j].size();
                if (deg[j] == 1) Q.push_back(j);
            }
            shuffle(Q.begin(), Q.end(), rnd);
            while (!Q.empty()) {
                int x = Q.back(); Q.pop_back();
                z.push_back(x);
                shuffle(G[x].begin(), G[x].end(), rnd);
                for (auto v : G[x]) {
                    if (--deg[v] == 1) Q.push_back(v);
                }
            }
            for (int j = 0; j < n; ++j) printf("%d%c", z[j], " \n"[j + 1 == n]);
        }
    }
    return 0;
}