//#pragma GCC optimize(3,"Ofast","inline")
//#pragma GCC optimize(2)
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
const int N = 505 + 5;
vector<int>ed[N];
vector<int>ans[N];
struct TreeD{
	ll sz[N], maxp[N], vis[N], sum, rt, cnt;	//点分治必备
	ll tmp[N];
	ll dis[N];
	void getrt(ll fa, ll u)		//求重心
	{
		sz[u] = 1, maxp[u] = 0;
		for (auto v : ed[u])
		{
			if (vis[v] || v == fa)
				continue;
			getrt(u, v);
			sz[u] += sz[v];
			if (maxp[u] < sz[v])
				maxp[u] = sz[v];
		}
		maxp[u] = max(sum - sz[u], maxp[u]);
		if (maxp[u] < maxp[rt])
			rt = u;
	}
	void divide(ll u,ll dep)	//点分部分
	{
		vis[u] = 1;
        ans[dep].push_back(u);
		for (auto v : ed[u])
		{
			if (vis[v])
				continue;
			maxp[rt = 0] = sum = sz[v];
			getrt(0, v);
			getrt(0, rt);
			divide(rt, dep + 1);
		}
	}
	void init(ll n)		//点分治，启动！
	{
		sum = maxp[rt = 0] = n;
		getrt(0, 1);
		getrt(0, rt);
		divide(rt, 1);
	}
};
int	main(){
    ios::sync_with_stdio(0); cin.tie(0);
    int T=1;
    //cin>>T;
    while(T--)
    {
        ll n;
        cin>>n;
        for(int i=1;i<n;i++){
            int u,v;
            cin>>u>>v;
            ed[u].push_back(v);
            ed[v].push_back(u);
        }
        TreeD x;
        x.init(n);
        for(int i=n;i>=1;i--){
            if(ans[i].size()){
                cout<<ans[i].size()<<" ";
                for(auto v:ans[i]){
                    cout<<v<<" ";
                }
                cout<<"\n";
            }
        }
    }
}
/*
5
1 2
1 3
1 4
4 5
*/