#include <bits/stdc++.h>
// #include <windows.h>
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
using namespace std;
//#pragma GCC optimize(3)
#define DB double
#define LL long long
#define ULL unsigned long long
#define in128 __int128
#define cint const int
#define cLL const LL
#define For(z,e1,e2) for(int z=(e1);z<=(e2);z++)
#define Rof(z,e1,e2) for(int z=(e2);z>=(e1);z--)
#define For_(z,e1,e2) for(int z=(e1);z<(e2);z++)
#define Rof_(z,e1,e2) for(int z=(e2);z>(e1);z--)
#define inint(e) scanf("%d",&e)
#define inll(e) scanf("%lld",&e)
#define inpr(e1,e2) scanf("%d%d",&e1,&e2)
#define in3(e1,e2,e3) scanf("%d%d%d",&e1,&e2,&e3)
#define outint(e) printf("%d\n",e)
#define outint_(e) printf("%d%c",e," \n"[i==n])
#define outint2_(e,e1,e2) printf("%d%c",e," \n"[(e1)==(e2)])
#define outll(e) printf("%lld\n",e)
#define outll_(e) printf("%lld%c",e," \n"[i==n])
#define outll2_(e,e1,e2) printf("%lld%c",e," \n"[(e1)==(e2)])
#define exc(e) if(e) continue
#define stop(e) if(e) break
#define ret(e) if(e) return
#define ll(e) (1ll*(e))
#define pb push_back
#define ft first
#define sc second
#define pii pair<int,int> 
#define pli pair<long long,int> 
#define vct vector 
#define clean(e) while(!e.empty()) e.pop()
#define all(ev) ev.begin(),ev.end()
#define sz(ev) ((int)ev.size())
#define debug(x) printf("%s=%d\n",#x,x)
#define x0 __xx00__
#define y1 __yy11__
#define ffo fflush(stdout)
cLL mod=998244353,G=404;
// cLL mod=1000000007ll;
// cLL mod[2]={1686688681ll,1666888681ll},base[2]={166686661ll,188868881ll};
template <typename Type> void get_min(Type &w1,const Type w2) { if(w2<w1) w1=w2; } template <typename Type> void get_max(Type &w1,const Type w2) { if(w2>w1) w1=w2; }
template <typename Type> Type up_div(Type w1,Type w2) { return (w1/w2+(w1%w2?1:0)); }
template <typename Type> Type gcd(Type X_,Type Y_) { Type R_=X_%Y_; while(R_) { X_=Y_; Y_=R_; R_=X_%Y_; } return Y_; } template <typename Type> Type lcm(Type X_,Type Y_) { return (X_/gcd(X_,Y_)*Y_); }
template <typename Type> Type md(Type w1,const Type w2=mod) { w1%=w2; if(w1<0) w1+=w2; return w1; } template <typename Type> Type md_(Type w1,const Type w2=mod) { w1%=w2; if(w1<=0) w1+=w2; return w1; }
void ex_gcd(LL &X_,LL &Y_,LL A_,LL B_) { if(!B_) { X_=1ll; Y_=0ll; return ; } ex_gcd(Y_,X_,B_,A_%B_); X_=md(X_,B_); Y_=(1ll-X_*A_)/B_; } LL inv(LL A_,LL B_=mod) { LL X_=0ll,Y_=0ll; ex_gcd(X_,Y_,A_,B_); return X_; }
template <typename Type> void add(Type &w1,const Type w2,const Type M_=mod) { w1=md(w1+w2,M_); } void mul(LL &w1,cLL w2,cLL M_=mod) { w1=md(w1*md(w2,M_),M_); } template <typename Type> Type pw(Type X_,Type Y_,Type M_=mod) { Type S_=1; while(Y_) { if(Y_&1) mul(S_,X_,M_); Y_>>=1; mul(X_,X_,M_); } return S_; }
template <typename Type> Type bk(vector <Type> &V_) { auto T_=V_.back(); V_.pop_back(); return T_; } template <typename Type> Type tp(stack <Type> &V_) { auto T_=V_.top(); V_.pop(); return T_; } template <typename Type> Type frt(queue <Type> &V_) { auto T_=V_.front(); V_.pop(); return T_; }
template <typename Type> Type bg(set <Type> &V_) { auto T_=*V_.begin(); V_.erase(V_.begin()); return T_; } template <typename Type> Type bk(set <Type> &V_) { auto T_=*prev(V_.end()); V_.erase(*prev(V_.end())); return T_; }
mt19937 gen(time(NULL)); int rd() { return abs((int)gen()); }
int rnd(int l,int r) { return rd()%(r-l+1)+l; }

void main_init()
{

}
cint N=120;
int n;
vct <int> v[N],ans1[N],ans2[N];
int siz[N],mxs[N];
void grt(int p,int fa)
{
    siz[p]=1,mxs[p]=0;
    for(auto i:v[p])
    {
        exc(i==fa);
        grt(i,p);
        siz[p]+=siz[i];
        get_max(mxs[p],siz[i]);
    }
    get_max(mxs[p],n-siz[p]);
}
int get_root(int p)
{
    grt(p,0);
    // printf("get root %d:",p);
    For(i,1,n) if(mxs[i]<mxs[p]) p=i;
    // printf(" %d\n",p);
    return p;
}
int up[N],dep[N];
void dfs(int p,int fa)
{
    dep[p]=dep[fa]+1,up[p]=fa;
    for(auto i:v[p])
    {
        exc(i==fa);
        dfs(i,p);
    }
}
int a[N];
void work(int w,bool opt)
{
    if(opt)
        For(i,1,n) ans1[i].swap(ans2[i]);
    For(i,1,n)
    {
        int t=ans1[i].back();
        For(round,1,w)
        {
            stop(!up[t]);
            t=up[t];
            ans1[i].pb(t);
            ans2[i].pb(ans2[i].back());
        }
    }
    int len=0;
    For(i,1,n) get_max(len,max(sz(ans1[i]),sz(ans2[i])));
    For(i,1,n) ans1[i].resize(len,ans1[i].back());
    For(i,1,n) ans2[i].resize(len,ans2[i].back());
    if(opt)
        For(i,1,n) ans1[i].swap(ans2[i]);
}
void main_solve()
{
    inint(n);
    // n=100;
    For_(i,1,n)
    {
        int x,y; inpr(x,y); x++,y++;
        // int x=i,y=i+1;
        v[x].pb(y),v[y].pb(x);
    }
    int rt=get_root(1);
    dfs(rt,0);
    For(i,1,n) ans1[i].pb(i),ans2[i].pb(i);
    work(3,true);
    work(13,false);
    work(27,true);
    work(n,false);
    work(n,true);
    For(i,1,n) ans1[i].pb(rt),ans2[i].pb(rt);
    int len=sz(ans1[1])-1;
    outint(len<<1);
    For(i,1,n)
        For(j,1,len) printf("%d %d%c",ans1[i][j]-1,ans1[i][j]-1," \n"[j==len]);
    For(i,1,n)
    {
        printf("%d ",i-1);
        For_(j,1,len) printf("%d %d ",ans2[i][j]-1,ans2[i][j]-1);
        printf("%d\n",ans2[i][len]-1);
    }
}
int main()
{
    // ios::sync_with_stdio(0); cin.tie(0);
    // freopen("in.txt","r",stdin);
    // freopen("out.txt","w",stdout);
    // srand(time(NULL));
    main_init();
    // int _; inint(_); For(__,1,_) // T>1 ?
        // printf("\n------------\n\n"),
        main_solve();
    return 0;
}
/*
 
*/