#include<bits/stdc++.h>
#define rep(i,s,n) for (int i = (int)(s); i < (int)(n); i++)
#define all(v) begin(v),end(v)
using namespace std;
using ll = long long;
using vl=vector<ll>;
using vvl=vector<vl>;
using vvvl=vector<vvl>;
using pll=pair<ll,ll>;
using vp=vector<pll>;
bool chmin(auto &a, auto b){ return a > b ? a = b, 1 : 0; }
bool chmax(auto &a, auto b){ return a < b ? a = b, 1 : 0; }
constexpr ll INF=1LL<<60;

int main(){
    cin.tie(0)->sync_with_stdio(0);

    ll n;
    cin>>n;
    vvl g(n);
    rep(i,0,2*n-3){
        ll u,v;
        cin>>u>>v;
        u--,v--;
        g[u].emplace_back(v);
        g[v].emplace_back(u);
    }
    vl d(n,-1);
    vl par(n,-1);
    vp ed;
    auto f=[&](auto sf,ll v,ll p)->void
    {
        par[v]=p;
        if(p>=0) d[v]=d[p]+1;
        for(auto u:g[v]){
            if(d[u]<0) sf(sf,u,v);
            else if(u!=par[v]&&d[u]<d[v]) ed.emplace_back(u,v);
        }
    };
    rep(i,0,n)if(d[i]<0) f(f,i,-1);
    vector<vp> a(n);
    for(auto [u,v]:ed){
        ll t=d[v]-d[u];
        a[t].emplace_back(u,v);
    }
    auto path=[&](pll p){
        auto [u,v]=p;
        assert(d[u]<d[v]);
        vl rs;
        while(1){
            assert(v>=0);
            rs.emplace_back(v);
            if(v==u) break;
            v=par[v];
        }
        return rs;
    };
    vvl rs(2);
    rep(i,2,n)if(a[i].size()>=2){
        rep(j,0,2) rs[j]=path(a[i][j]);
        break;
    }
    if(rs[0].empty()){
        ll m=n-2;
        assert(*max_element(all(d))==n-1);
        assert((ll)ed.size()==m);
        sort(all(ed));
        rep(i,0,m-1)if(ed[i].first==ed[i+1].first){
            auto [u,v]=ed[i];
            auto [x,y]=ed[i+1];
            if(d[v]>d[y]) swap(v,y);
            ll len=d[y]-d[v]+1;
            rs[0]=path(a[len][0]);
            rs[1]=path(pll(v,y));
            rs[1].emplace_back(u);
            break;
        }
        sort(all(ed),[](pll p,pll q){return p.second<q.second;});
        rep(i,0,m-1)if(ed[i].second==ed[i+1].second){
            auto [u,v]=ed[i];
            auto [x,y]=ed[i+1];
            if(d[u]>d[x]) swap(u,x);
            ll len=d[x]-d[u]+1;
            rs[0]=path(a[len][0]);
            rs[1]=path(pll(u,x));
            rs[1].emplace_back(v);
            break;
        }
    }
    ll sz=rs[0].size();
    cout<<sz<<endl;
    rep(i,0,sz) cout<<rs[0][i]+1<<" \n"[i==sz-1];
    rep(i,0,sz) cout<<rs[1][i]+1<<" \n"[i==sz-1];
}