#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
using namespace std;
using ll = long long int;
template<typename T>
ostream& operator+(ostream& out, const vector<T> &vec){
    for(const auto &x : vec){
        out<<x<<" ";
    }
    out<<"\n";
    return out;
}
template<typename T>
ostream& operator*(ostream& out, const vector<T> &vec){
    for(const auto &x : vec){
        out+x;
    }
    return out;
}
template<typename T>
istream& operator>>(istream& in, vector<T> &vec){
    for(auto &x : vec){
        in>>x;
    }
    return in;
}
struct my_set{
    int offset = 0;
    set<int> s;
    auto view(){
        return s | views::transform([&](int x){
            return x ^ offset;
        });
    }
    void add(int elem){
        s.insert(elem ^ offset);
    }
    void add_offset(int more_offset){
        offset ^= more_offset;
    }
    bool has(int elem){
        return s.count(elem ^ offset);
    }
    int size() const {
        return s.size();
    }
    void add_set(my_set &other){
        if(other.size() > size()) swap(*this, other);
        for(int x : other.view()) add(x);
    }
};
void solve(){
    int n;
    cin>>n;
    vector<vector<int>> t(n);
    for(int i=1;i<n;i++){
        int u,v;
        cin>>u>>v;
        --u; --v;
        t[u].push_back(v);
        t[v].push_back(u);
    }
    vector<my_set> grundy_vals(n);
    vector<int> grundy(n);
    vector<int> sub(n);
    auto dfs = [&](int u, int p, auto&& dfs) -> void {
        int ch = 0;
        int grundy_xor = 0;
        for(int v : t[u]){
            if(v == p) continue;
            dfs(v, u, dfs);
            grundy_xor ^= grundy[v];
            sub[u] += sub[v];
            ch++;
        }
        if(ch == 0){
            grundy_vals[u].add(0);
            grundy[u] = 1;
            return;
        }
        sort(t[u].begin(), t[u].end(), [&](int a, int b){
            return grundy_vals[a].size() > grundy_vals[b].size();
        });
        for(auto &v : t[u]){
            if(v == p) continue;
            grundy_vals[v].add_offset(grundy_xor ^ grundy[v]);
            grundy_vals[u].add_set(grundy_vals[v]);
        }
        sort(t[u].begin(), t[u].end(), [&](int a, int b){
            return sub[a] > sub[b];
        });
        if(ch == 1){
            grundy_vals[u].add(grundy[t[u][0]]);
            grundy[u] = grundy[t[u][0]] + 1;
            return;
        }
        int max_mex_diff = 1;
        while(max_mex_diff <= sub[t[u][1]]) max_mex_diff <<= 1;
        max_mex_diff *= 2;
        grundy_vals[u].add(grundy_xor);
        int mex = max(0, grundy[t[u][0]] - max_mex_diff);
        while(grundy_vals[u].has(mex)) mex++;
        grundy[u] = mex;
    };
    dfs(0, -1, dfs);
    vector<int> res;
    auto dfs2 = [&](int u, int p, int c_xor, auto&& dfs) -> void {
        int grundy_xor = 0;
        for(int v : t[u]){
            if(v == p) continue;
            grundy_xor ^= grundy[v];
        }
        if((grundy_xor ^ c_xor) == 0){
            res.push_back(u + 1);
        }
        for(int v : t[u]){
            if(v == p) continue;
            dfs(v, u, grundy_xor ^ c_xor ^ grundy[v], dfs);
        }
    };
    dfs2(0, -1, 0, dfs2);
    if(res.size() == 0){
        cout<<"Bob\n";
        return;
    }
    cout<<"Alice\n";
    cout<<res.size()<<"\n";
    cout+res;
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}