#include<bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include"debug.h"
#else
#define debug(...) void()
#endif
#define all(x) (x).begin(),(x).end()
template<class T>
auto ary(T *a,int l,int r){
	return vector<T>{a+l,a+1+r};
}
using ll=long long;
using ull=unsigned ll;
const int N=1e5+10;
int T,n,m,s,t;
vector<int>to[N];
vector<vector<int>>ans;
int fa[N],cnt[N],siz[N];
int find(int x){
	return fa[x]==x?x:fa[x]=find(fa[x]);
}
void link(int x,int y,int w){
	x=find(x),y=find(y);
	if(x==y)cnt[x]+=w;
	else cnt[y]+=cnt[x]+w,siz[y]+=siz[x],fa[x]=y;
}
vector<int>stk;
bool dfs(int u,int fa=0){
	stk.push_back(u);
	if(u==t)return ans.push_back(stk),1;
	for(int v:to[u])if(v^fa){
		if(dfs(v,u))return 1;
	}
	stk.pop_back();
	return 0;
}
void solve(const vector<tuple<int,int,int>> &E,int k){
	if(k==1){
		auto [u,v,w]=E[0];
		s=u,t=v,ans={{u,v}};
		return;
	}
	iota(fa,fa+1+n,0);
	fill(cnt,cnt+1+n,0);
	fill(siz+1,siz+1+n,1);
	for(auto [u,v,w]:E)link(u,v,w);
	int rt=0,mx=0;
	for(int i=1;i<=n;i++)if(fa[i]==i&&siz[i]>1){
		int val=(cnt[i]-1)/(siz[i]-1)+1;
		if(val>mx)mx=val,rt=i;
	}
	vector<tuple<int,int,int>>ne,ret;
	for(auto [u,v,w]:E){
		if(find(u)==rt)ne.push_back({u,v,w});
	}
	iota(fa,fa+1+n,0);
	vector<pair<int,int>>cur;
	for(auto [u,v,w]:ne){
		int x=find(u),y=find(v);
		if(x!=y){
			fa[x]=y;
			cur.push_back({u,v});
			if(w>1)ret.push_back({u,v,w-1});
		}else ret.push_back({u,v,w});
	}
	solve(ret,k-1);
	for(auto [u,v]:cur){
		to[u].push_back(v),to[v].push_back(u);
	}
	stk.clear(),dfs(s);
	for(int i=1;i<=n;i++)to[i].clear();
}
void get(){
	scanf("%d%d",&n,&m);
	vector<tuple<int,int,int>>E(m);
	for(auto &[u,v,w]:E){
		scanf("%d%d",&u,&v),w=1;
		if(u>v)swap(u,v);
	}
	sort(all(E));
	int len=0;
	for(int i=1;i<E.size();i++){
		auto &[u1,v1,w1]=E[len];
		auto &[u2,v2,w2]=E[i];
		if(u1==u2&&v1==v2)w1++;
		else E[++len]=E[i];
	}
	solve(E,(m-1)/(n-1)+1);
	printf("%d %d\n",s,t);
	for(const auto &x:ans){
		printf("%ld",x.size());
		for(int y:x)printf(" %d",y);
		puts("");
	}
}
int main(){
	for(scanf("%d",&T);T--;)get();
	return 0;
}
#ifdef DEBUG
#include"debug.hpp"
#endif