#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define mp make_pair
#define si(x) int(x.size())
const int mod=998244353,MAX=300005,INF=15<<26;

vector<int> G[MAX];
int sz[MAX];

void mk(int u,int p){
    sz[u]=1;
    for(int to:G[u]){
        if(to==p) continue;
        mk(to,u);
        sz[u]+=sz[to];
    }
}

vector<int> ans;

int X;

void solve(int u,int p){
    int sv=X;
    
    X^=sz[u];
    for(int to:G[u]){
        if(to==p) continue;
        X^=sz[to];
    }
    
    if(X==0) ans.push_back(u);
    
    for(int to:G[u]){
        if(to==p) continue;
        solve(to,u);
    }
    
    X=sv;
}

int main(){
    
    std::ifstream in("text.txt");
    std::cin.rdbuf(in.rdbuf());
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int N;cin>>N;
    for(int i=0;i<N-1;i++){
        int a,b;cin>>a>>b;a--;b--;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    mk(0,-1);
    X=N;
    solve(0,-1);
    
    if(si(ans)){
        cout<<"Alice\n";
        cout<<si(ans)<<"\n";
        sort(all(ans));
        for(int x:ans) cout<<x+1<<" ";
        cout<<"\n";
    }else{
        cout<<"Bob\n";
    }
}