/* #region Head */ #include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; using pll = pair; using vll = vector; using vvll = vector; using vld = vector; using vvd = vector; using vs = vector; using vvs = vector; #define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i)) #define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i)) #define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i)) #define REPD(i, m, n, d) for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d)) #define REPMD(i, m, n, d) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d)) #define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++) #define ALL(x) begin(x), end(x) #define SIZE(x) ((ll)(x).size()) #define PREM(c) \ sort(all(c)); \ for (bool c##p = 1; c##p; c##p = next_permutation(all(c))) #define UNIQ(v) v.erase(unique(ALL(v)), v.end()); constexpr ll INF = 1'010'000'000'000'000'017LL; constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7 constexpr ld EPS = 1e-12; constexpr ld PI = 3.14159265358979323846; // vector入力 template istream &operator>>(istream &is, vector &vec) { for (T &x : vec) is >> x; return is; } // vector出力 (for dump) template ostream &operator<<(ostream &os, vector &vec) { ll len = SIZE(vec); os << "{"; for (int i = 0; i < len; i++) os << vec[i] << (i == len - 1 ? "" : ", "); os << "}"; return os; } // vector出力 (inline) template ostream &operator>>(ostream &os, vector &vec) { ll len = SIZE(vec); for (int i = 0; i < len; i++) os << vec[i] << (i == len - 1 ? "\n" : " "); return os; } // pair入力 template istream &operator>>(istream &is, pair &pair_var) { is >> pair_var.first >> pair_var.second; return is; } // pair出力 template ostream &operator<<(ostream &os, pair &pair_var) { os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } // map出力 template ostream &operator<<(ostream &os, map &map_var) { os << "{"; REPI(itr, map_var) { os << *itr; itr++; if (itr != map_var.end()) os << ", "; itr--; } os << "}"; return os; } // set 出力 template ostream &operator<<(ostream &os, set &set_var) { os << "{"; REPI(itr, set_var) { os << *itr; itr++; if (itr != set_var.end()) os << ", "; itr--; } os << "}"; return os; } // dump #define DUMPOUT cerr void dump_func() { DUMPOUT << endl; } template void dump_func(Head &&head, Tail &&... tail) { DUMPOUT << head; if (sizeof...(Tail) > 0) { DUMPOUT << ", "; } dump_func(move(tail)...); } // chmax (更新「される」かもしれない値が前) template > bool chmax(T &xmax, const U &x, Comp comp = {}) { if (comp(xmax, x)) { xmax = x; return true; } return false; } // chmin (更新「される」かもしれない値が前) template > bool chmin(T &xmin, const U &x, Comp comp = {}) { if (comp(x, xmin)) { xmin = x; return true; } return false; } // ローカル用 #define DEBUG_ #ifdef DEBUG_ #define DEB #define dump(...) \ DUMPOUT << " " << string(#__VA_ARGS__) << ": " \ << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" \ << endl \ << " ", \ dump_func(__VA_ARGS__) #else #define DEB if (false) #define dump(...) #endif struct AtCoderInitialize { static constexpr int IOS_PREC = 15; static constexpr bool AUTOFLUSH = false; AtCoderInitialize() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); cout << fixed << setprecision(IOS_PREC); if (AUTOFLUSH) cout << unitbuf; } } ATCODER_INITIALIZE; /* #endregion */ using Weight = ll; using Flow = ll; // エッジ(本来エッジは双方向だが,ここでは単方向で管理) struct Edge { ll src; // エッジ始点となる頂点 ll dst; // エッジ終点となる頂点 Weight weight; // 重み Flow cap; Edge() : src(0), dst(0), weight(0) {} Edge(ll src, ll dst, Weight weight) : src(src), dst(dst), weight(weight) {} }; using Node = vector; // 同じ頂点を始点とするエッジ集合 using Graph = vector; // graph[i] := 頂点 i を始点とするエッジ集合 // using Array = vector; // using Matrix = vector; // 双方向のエッジを追加する void add_edge(Graph &g, ll a, ll b, Weight w = 1) { g[a].emplace_back(a, b, w); g[b].emplace_back(b, a, w); } // 単方向のアークを追加する void add_arc(Graph &g, ll a, ll b, Weight w = 1) { g[a].emplace_back(a, b, w); } ostream &operator<<(ostream &os, Edge &edge) { os << "(" << edge.src << " -> " << edge.dst << ", " << edge.weight << ")"; return os; } /** Problem */ void solve() { ll n; cin >> n; vll u(n - 1), v(n - 1); REP(i, 0, n - 1) { cin >> u[i] >> v[i]; } Graph graph(n, Node(0)); REP(i, 0, n - 1) { add_edge(graph, u[i], v[i]); } vll cnt(n, 0); // 橋の数×2 queue que; // 「訪問予定」頂点リスト // 初期条件 (頂点 0 を初期頂点とする) cnt[0] = 0; que.push(graph[0]); // 頂点 0 を「訪問予定」頂点リストに追加 // BFS 開始 (キューが空になるまで探索を行う) while (!que.empty()) { Node current = que.front(); // キューから先頭頂点を取り出す que.pop(); // cuerrent から辿れる頂点をすべて調べる for (Edge edge : current) { if (cnt[edge.dst] > 0) { cnt[edge.src]++; cnt[edge.dst]++; continue; // 訪問済み } // 未訪問の頂点 nv について距離情報を更新してキューに追加する cnt[edge.src]++; cnt[edge.dst]++; que.push(graph[edge.dst]); } } // dump(graph); // dump(cnt); string alice = "Alice", bob = "Bob"; ll zeros = 0; REP(i, 0, n) { if (cnt[i] == 0) zeros++; } if (zeros >= 2) { cout << alice << endl; return; } else if (zeros == 0) { cout << bob << endl; return; } ll leafs = 0; REP(i, 0, n) { if (cnt[i] == 2) leafs++; } cout << (leafs > 0 ? alice : bob) << endl; } /** * エントリポイント. * @return 0. */ int main() { solve(); return 0; }