#include <bits/stdc++.h>
using namespace std;
#define U(i,l,r) for (int i(l),END##i(r); i<=END##i; ++i)
#define D(i,l,r) for (int i(l),END##i(r); i>=END##i; --i)
#define ms(x, v) memset(x, v, sizeof(x))
#define il __attribute__((always_inline))
#define vc vector
#define ar array
#define pb push_back
#define eb emplace_back
#define el '\n'
using ll = long long;

void solve() {
	int n, m; cin >> n >> m;
	vc<set<int>> adj(n);
	vc<int> to(m * 2), deg(n);
	vc<list<int>> path(m * 2);

	U (i, 0, m - 1) {
		int u, v; cin >> u >> v; --u; --v;
		to[i * 2] = v; adj[u].insert(i * 2);
		to[i * 2 + 1] = u; adj[v].insert(i * 2 + 1);
		++deg[u]; ++deg[v];
	}

	priority_queue<pair<int, int>, vc<pair<int, int>>, greater<>> pq;
	U (i, 0, n - 1) pq.emplace(deg[i], i);


	const int k = (m - 1) / (n - 1) + 1;
	while (pq.size()) {
		auto [d, u] = pq.top(); pq.pop();
		if (d != deg[u]) continue;

		vc<int> p(adj[u].begin(), adj[u].end()); adj[u].clear();
		sort(p.begin(), p.end(), [&](int x, int y) { return to[x] < to[y]; });
		vc<int> vert(p.size());
		U (i, 0, p.size() - 1) vert[i] = to[p[i]];
		vert.erase(unique(vert.begin(), vert.end()), vert.end());
		
		U (i, k - 1, p.size() - 1) {
			if (to[p[i]] != to[p[i - k + 1]]) continue;

			// have answer found
			cout << to[p[i]] + 1 << ' ' << u + 1 << el;
			U (j, i - k + 1, i) {
				int e = p[j] ^ 1;
				cout << path[e].size() + 2 << ' ' << to[p[i]] + 1;
				for (int v : path[e])
					cout << ' ' << v + 1;
				cout << ' ' << u + 1 << endl;
			}
			return;
		}
		for (int e : p) {
			--deg[to[e]];
			adj[to[e]].erase(e ^ 1);
			// clog << "-" << u << ' ' << to[e] << endl;
		}

		int t = max<int>(k - 1, (p.size() + 1) / 2);
		U (i, t, p.size() - 1) {
			int e1 = p[i - t] ^ 1, e2 = p[i], x = to[e1 ^ 1], y = to[e2];
			path[e1].pb(u); path[e1].splice(path[e1].end(), path[e2]);
			path[e2 ^ 1].pb(u); path[e2 ^ 1].splice(path[e2 ^ 1].end(), path[e1 ^ 1]);
			to[e1] = y; to[e1 ^ 1] = x;
			swap(path[e2 ^ 1], path[e1 ^ 1]);

			adj[x].insert(e1);
			adj[y].insert(e1 ^ 1);
			// clog << "+" << x << ' ' << y << endl;
			++deg[x]; ++deg[y];
		}

		for (int x : vert)
			pq.emplace(deg[x], x);
	}

	assert(0);
}

int main() {
	// freopen("ava.in", "r", stdin);
	// freopen(".out", "w", stdout);
	ios::sync_with_stdio(0);

	int t; cin >> t;
	while (t--)
		solve();
}