#include<bits/stdc++.h>

using namespace std;

#define F first 
#define S second 
#define pb push_back
#define int long long

vector<int>node[100005];
bool vis[100005];
int dep[100005],pp[100005];
int id[100005];
pair<int,int>ans[100005];
int now=0,t1,t2;

void dfs(int v,int pre){

    pp[v]=pre;
    dep[v]=dep[pre]+1;
    vis[v]=1;
    for(int ii:node[v]){
        if(ii==pre) continue;
        if(!vis[ii]){
            dfs(ii,v);
        }
        else if(dep[v]>dep[ii]){
            int dd=dep[v]-dep[ii];
            int g1=v,g2=ii;
            if(dep[g1]<dep[g2]) swap(g1,g2);
            dd=abs(dd);
            if(id[dd]){
                now=dd;t1=g1,t2=g2;
            }
            else ans[dd].F=g1,ans[dd].S=g2;
            id[dd]=g1;
        }
    }
}

void solve(){
    int n;
    cin>>n;
    for(int i=1;i<=n*2-3;i++){
        int g,h;
        cin>>g>>h;
        node[g].pb(h);
        node[h].pb(g);
    }
    dfs(1,1);
    if(!now) {
        now=3;
        t1=id[n-1],t2=id[n];
        pp[t1]=1,pp[1]=t2;
    }
    

    int g1=ans[now].F,h1=ans[now].S;
    swap(g1,h1);swap(t1,t2);
    // cerr<<now<<"\n";
    cout<<now+1<<"\n";
    while(h1!=g1) cout<<h1<<" ",h1=pp[h1];
    cout<<g1<<"\n";

    while(t2!=t1) cout<<t2<<" ",t2=pp[t2];
    cout<<t1<<"\n";
}

signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    solve();
    return 0;
}