#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pii pair<int,int>
#define pb push_back
const int N = 5e5+5;
int n,m,K,top,stk[N];
vector<int> path,e[N];
struct dsu{
	vector<int> fa;
	void init(){
		fa.pb(0);
		for(int i=1;i<=n;i++) fa.pb(i);
	}
	int find(int u){
		if(u==fa[u]) return fa[u];
		return fa[u] = find(fa[u]);
	}
	void merge(int u,int v){
		u = find(u),v = find(v);
		if(u==v) return ;
		fa[u] = v;
	}
};
bool get_path(int u,int fa,int ed){
	stk[++top] = u;
	if(u==ed){
		while(top) path.pb(stk[top--]);
		reverse(path.begin(),path.end());
		return 1;
	}
	for(int v:e[u]){
		if(v==fa) continue;
		if(get_path(v,u,ed)) return 1;
	}
	top--;
	return 0;
}
void solve(){
	cin >> n >> m;K = (m-1)/(n-1)+1;
	vector<dsu> s(K+1);
	vector<vector<pii >> g(K+1); 
	for(int i=1;i<=K;i++) s[i].init();
	for(int i=1,u,v;i<=m;i++){
		cin >> u >> v;
		int l = 1,r = K,pos = -1;
		while(l<=r){
			int mid = (l+r)>>1;
			if(s[mid].find(u) != s[mid].find(v)){
				pos = mid;
				r = mid-1;
			}else{
				l = mid+1;
			}
		}
		if(pos==-1) break;
		s[pos].merge(u,v),g[pos].pb({u,v});
	}
	int x = g[K][0].fi,y = g[K][0].se;
	cout << x << ' ' << y << '\n';
	for(int i=1;i<=K;i++){
		top = 0,path.clear();
		for(int u=1;u<=n;u++) e[u].clear();
		for(pii r:g[i]) e[r.fi].pb(r.se),e[r.se].pb(r.fi);
		get_path(x,0,y);
		cout << path.size() << ' ';
		for(int u:path) cout << u << ' ';
		cout << '\n';
	}
}
int main(){
	cin.tie(0),cout.tie(0);
	ios::sync_with_stdio(0);
	int T;cin >> T;
	while(T--) solve();
	return 0;
}