//Shirosaki Hana kawaii
#include<bits/stdc++.h>
const int QWQ=2e5+5;
using namespace std;
inline int read(){
    int x=0,f=1; char ch=getchar();
    for (;ch<'0'||ch>'9';ch=getchar())
        if (ch=='-') f=-1;
    for (;ch>='0'&&ch<='9';ch=getchar())
        x=(x<<1)+(x<<3)+(ch^48);
    return x*f;
}
int T,n,m,K,fa[QWQ],pre[QWQ],vis[QWQ];
vector<int> E[QWQ],vec;
int get(int k){
	if (fa[k]==k) return k;
	return fa[k]=get(fa[k]);
}
signed main(){
	for (T=read();T--;){
		n=read(),m=read(),K=ceil(m*1.0/(n-1));
		for (int t=1;t<=K;t++)
		for (int i=1;i<=n;i++) fa[(t-1)*n+i]=(t-1)*n+i;
		for (int i=1;i<=m;i++){
			int u=read(),v=read();
			for (int t=1;t<=K;t++){
				int A=get((t-1)*n+u);
				int B=get((t-1)*n+v);
				if (A!=B){
					E[(t-1)*n+u].push_back((t-1)*n+v);
					E[(t-1)*n+v].push_back((t-1)*n+u);
					fa[B]=A; break;
				}
			}
		}
		int u=0,v=0;
		for (int i=1;i<=n;i++)
			if (fa[(K-1)*n+i]!=(K-1)*n+i)
				u=fa[(K-1)*n+i]-(K-1)*n,v=i;
		printf("%d %d\n",u,v);
		for (int d=1;d<=K;d++){
			int s=(d-1)*n+u,t=(d-1)*n+v;
			queue<int> q; q.push(s),vis[s]=1;
			while (!q.empty()){
				int now=q.front(); q.pop();
				for (int to:E[now]) if (!vis[to])
					pre[to]=now,q.push(to),vis[to]=1;
			}
			vec.clear(),vec.push_back(v);
			for (int i=pre[t];i;i=pre[i])
				vec.push_back(i-(d-1)*n);
			reverse(vec.begin(),vec.end());
			printf("%d ",(int)vec.size());
			for (int x:vec) printf("%d ",x); puts("");
		}
		for (int i=1;i<=K*n;i++)
			E[i].clear(),pre[i]=vis[i]=0;
	}
	return 0;
}