#include<iostream>
#include<cstdio>
#include<vector>
#define N 100
using namespace std;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
int n,len,tong[N+1],length,fa[N+1],sfa[N+1],delta[N+1],depth[N+1],ps[N+1];
vector<int>E[N+1];
vector<int>v[N+1];
bool used[N+1];
void add(int x,int y)
{
	E[x].push_back(y),E[y].push_back(x);
	return;
}
void dfs(int x)
{
	used[x]=1;
	for (int i=0;i<E[x].size();++i)
		if (!used[E[x][i]])
			fa[E[x][i]]=x,depth[E[x][i]]=depth[x]+1,dfs(E[x][i]);
	return;
}
void dfs2(int x,int d)
{
	if (!(depth[x]&((1<<len)-1))) sfa[x]=d,d=x;
	for (int i=0;i<E[x].size();++i)
		if (fa[E[x][i]]==x)
			dfs2(E[x][i],d);
	return;
}
int main()
{
	int x,y;
	bool op,op2;
	n=read();
	for (int i=1;i<=n;++i) ps[i]=i;
	for (int i=1;i<=n-1;++i) x=read()+1,y=read()+1,add(x,y);
	dfs(1);
	for (int i=0;i<7;++i)
	{
		len=i;
		for (int j=1;j<=n;++j) sfa[j]=delta[j]=0;
		dfs2(1,0),op=op2=0;
		for (int j=2;j<=n;++j)
		{
			if (sfa[ps[j]]&&((depth[ps[j]]>>i)&1)) op=1;
			if (sfa[ps[j]]&&(!((depth[ps[j]]>>i)&1))) op2=1;
		}
		if (op)
		{
			if (!op2)
			{
				for (int j=1;j<=n;++j)
				{
					if (sfa[ps[j]]&&((depth[ps[j]]>>i)&1))
					{
						x=ps[j];
						while (x!=sfa[ps[j]]) x=fa[x],v[j].push_back(x);
						ps[j]=sfa[ps[j]];
					}
					else
					{
						for (int k=1;k<=(1<<i);++k) v[j].push_back(ps[j]);
					}
				}
			}
			else
			{
				for (int j=1;j<=n;++j)
				{
					if (sfa[ps[j]]&&(!((depth[ps[j]]>>i)&1)))
					{
						x=ps[j],tong[length=1]=x;
						while (x!=sfa[ps[j]]) x=fa[x],tong[++length]=x;
						for (int k=2;k<=length;++k) v[j].push_back(tong[k]);
						for (int k=length-1;k>=1;--k) v[j].push_back(tong[k]);
					}
					else if (sfa[ps[j]]&&((depth[ps[j]]>>i)&1))
					{
						for (int k=1;k<=(1<<i);++k) v[j].push_back(ps[j]);
						x=ps[j];
						while (x!=sfa[ps[j]]) x=fa[x],v[j].push_back(x);
						ps[j]=sfa[ps[j]];
					}
					else
					{
						for (int k=1;k<=(1<<(i+1));++k) v[j].push_back(ps[j]);
					}
				}
			}
		}
		else break;
	}
	printf("%d\n",(v[1].size()<<1)+1);
	for (int i=1;i<=n;++i)
	{
		for (int j=0;j<v[i].size();++j) printf("%d %d ",v[i][j]-1,v[i][j]-1);
		puts("0");
	}
	for (int i=1;i<=n;++i)
	{
		printf("%d ",i-1);
		for (int j=0;j+1<v[i].size();++j) printf("%d %d ",v[i][j]-1,v[i][j]-1);
		printf("%d 0\n",v[i].back()-1);
	}
	return 0;
}