#line 2 "/Users/noya2/Desktop/Noya2_library/template/template.hpp" using namespace std; #include #line 1 "/Users/noya2/Desktop/Noya2_library/template/inout_old.hpp" namespace noya2 { template ostream &operator<<(ostream &os, const pair &p){ os << p.first << " " << p.second; return os; } template istream &operator>>(istream &is, pair &p){ is >> p.first >> p.second; return is; } template ostream &operator<<(ostream &os, const vector &v){ int s = (int)v.size(); for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i]; return os; } template istream &operator>>(istream &is, vector &v){ for (auto &x : v) is >> x; return is; } void in() {} template void in(T &t, U &...u){ cin >> t; in(u...); } void out() { cout << "\n"; } template void out(const T &t, const U &...u){ cout << t; if (sizeof...(u)) cout << sep; out(u...); } template void out(const vector> &vv){ int s = (int)vv.size(); for (int i = 0; i < s; i++) out(vv[i]); } struct IoSetup { IoSetup(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); cerr << fixed << setprecision(7); } } iosetup_noya2; } // namespace noya2 #line 1 "/Users/noya2/Desktop/Noya2_library/template/const.hpp" namespace noya2{ const int iinf = 1'000'000'007; const long long linf = 2'000'000'000'000'000'000LL; const long long mod998 = 998244353; const long long mod107 = 1000000007; const long double pi = 3.14159265358979323; const vector dx = {0,1,0,-1,1,1,-1,-1}; const vector dy = {1,0,-1,0,1,-1,-1,1}; const string ALP = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; const string alp = "abcdefghijklmnopqrstuvwxyz"; const string NUM = "0123456789"; void yes(){ cout << "Yes\n"; } void no(){ cout << "No\n"; } void YES(){ cout << "YES\n"; } void NO(){ cout << "NO\n"; } void yn(bool t){ t ? yes() : no(); } void YN(bool t){ t ? YES() : NO(); } } // namespace noya2 #line 1 "/Users/noya2/Desktop/Noya2_library/template/utils.hpp" namespace noya2{ unsigned long long inner_binary_gcd(unsigned long long a, unsigned long long b){ if (a == 0 || b == 0) return a + b; int n = __builtin_ctzll(a); a >>= n; int m = __builtin_ctzll(b); b >>= m; while (a != b) { int mm = __builtin_ctzll(a - b); bool f = a > b; unsigned long long c = f ? a : b; b = f ? b : a; a = (c - b) >> mm; } return a << min(n, m); } template T gcd_fast(T a, T b){ return static_cast(inner_binary_gcd(abs(a),abs(b))); } long long sqrt_fast(long long n) { if (n <= 0) return 0; long long x = sqrt(n); while ((x + 1) * (x + 1) <= n) x++; while (x * x > n) x--; return x; } template T floor_div(const T n, const T d) { assert(d != 0); return n / d - static_cast((n ^ d) < 0 && n % d != 0); } template T ceil_div(const T n, const T d) { assert(d != 0); return n / d + static_cast((n ^ d) >= 0 && n % d != 0); } template void uniq(vector &v){ sort(v.begin(),v.end()); v.erase(unique(v.begin(),v.end()),v.end()); } template inline bool chmin(T &x, U y) { return (y < x) ? (x = y, true) : false; } template inline bool chmax(T &x, U y) { return (x < y) ? (x = y, true) : false; } template inline bool range(T l, T x, T r){ return l <= x && x < r; } } // namespace noya2 #line 8 "/Users/noya2/Desktop/Noya2_library/template/template.hpp" #define rep(i,n) for (int i = 0; i < (int)(n); i++) #define repp(i,m,n) for (int i = (m); i < (int)(n); i++) #define reb(i,n) for (int i = (int)(n-1); i >= 0; i--) #define all(v) (v).begin(),(v).end() using ll = long long; using ld = long double; using uint = unsigned int; using ull = unsigned long long; using pii = pair; using pll = pair; using pil = pair; using pli = pair; namespace noya2{ /* ~ (. _________ . /) */ } using namespace noya2; #line 2 "c.cpp" #line 2 "/Users/noya2/Desktop/Noya2_library/tree/RerootingDP.hpp" #line 4 "/Users/noya2/Desktop/Noya2_library/tree/RerootingDP.hpp" namespace noya2 { template struct RerootingDP { struct edge { int to, idx, xdi; }; RerootingDP(int _n = 0) : n(_n) { es.resize(n); } void add_edge(int u, int v, int idx1, int idx2) { es[u].push_back({v, idx1, idx2}); es[v].push_back({u, idx2, idx1}); } vector build(int v = 0) { root = v; outs.resize(n); subdp.resize(n); in.resize(n), up.resize(n); int tnow = 0; dfs(root, -1, tnow); return subdp; } vector reroot() { reverse_edge.resize(n); reverse_edge[root] = e(); reverse_dp.resize(n); answers.resize(n); bfs(root); return answers; } V get(int r, int v) { if (r == v) return answers[r]; if (!(in[v] < in[r] && up[r] <= up[v])) return subdp[v]; int le = 0, ri = outs[v].size(); while (ri - le > 1) { int md = (le + ri) / 2; if (in[es[v][md].to] <= in[r]) le = md; else ri = md; } return reverse_dp[es[v][le].to]; } const vector &operator[](int idx) const { return es[idx]; } private: int n, root; vector> es; vector> outs; vector reverse_edge; vector subdp, reverse_dp, answers; vector in, up; void dfs(int v, int p, int &t) { E val = e(); in[v] = t++; for (auto &u : es[v]) { if (u.to == p && u.to != es[v].back().to) swap(u, es[v].back()); if (u.to == p) continue; dfs(u.to, v, t); E nval = put_edge(subdp[u.to], u.idx); outs[v].emplace_back(nval); val = merge(val, nval); } subdp[v] = put_vertex(val, v); up[v] = t; } void bfs(int v) { int siz = outs[v].size(); vector lui(siz + 1), rui(siz + 1); lui[0] = e(), rui[siz] = e(); for (int i = 0; i < siz; i++) lui[i + 1] = merge(lui[i], outs[v][i]); for (int i = siz - 1; i >= 0; i--) rui[i] = merge(outs[v][i], rui[i + 1]); for (int i = 0; i < siz; i++) { reverse_dp[es[v][i].to] = put_vertex(merge(merge(lui[i], rui[i + 1]), reverse_edge[v]), v); reverse_edge[es[v][i].to] = put_edge(reverse_dp[es[v][i].to], es[v][i].xdi); bfs(es[v][i].to); } answers[v] = put_vertex(merge(lui[siz], reverse_edge[v]), v); } }; } // namespace noya2 #line 4 "c.cpp" pii op(pii a, pii b){ return pii(a.first+b.first,a.second+b.second); } pii e(){ return pii(0,0); } pii pute(pii x, int){ return pii(max(x.first,x.second),x.first); } pii putv(pii x, int){ return pii(x.first,x.second+1); } void solve(){ int n; in(n); RerootingDP g(n); rep(i,n-1){ int u, v; in(u,v); u--, v--; g.add_edge(u,v,-1,-1); } g.build(); int ans = iinf; for (auto x : g.reroot()){ chmin(ans,x.second); } out(ans); } int main(){ int t = 1; //in(t); while (t--) { solve(); } }