#pragma GCC optimize ("O3") #include "bits/stdc++.h" using namespace std; using ll = long long int; #define debugos cout #define debug(v) {printf("L%d %s > ",__LINE__,#v);debugos<<(v)< ",__LINE__,#v);for(auto e:(v)){debugos< ",__LINE__,#m);for(int x=0;x<(w);x++){debugos<<(m)[x]<<" ";}debugos<\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){debugos<<(m)[y][x]<<" ";}debugos< f) { if (!assertion) { cerr << "assertion fault:" << endl; f(); abort(); } } template inline ostream& operator <<(ostream &o, const pair p) { o << '(' << p.first << ':' << p.second << ')'; return o; } template inline ostream& _ostream_vecprint(ostream& os, const Vec& a) { os << '['; for (const auto& e : a) os << ' ' << e << ' '; os << ']'; return os; } template inline ostream& operator<<(ostream& o, const vector& v) { return _ostream_vecprint(o, v); } template inline ostream& operator<<(ostream& o, const array& v) { return _ostream_vecprint(o, v); } template inline T& chmax(T& to, const T& val) { return to = max(to, val); } template inline T& chmin(T& to, const T& val) { return to = min(to, val); } void bye(string s, int code = 0) { cout << s << endl; exit(code); } mt19937_64 randdev(8901016); template::value>::type* = nullptr> inline T rand(T l, T h, Random& rand = randdev) { return uniform_int_distribution(l, h)(rand); } template::value>::type* = nullptr> inline T rand(T l, T h, Random& rand = randdev) { return uniform_real_distribution(l, h)(rand); } #if defined(_WIN32) || defined(_WIN64) #define getchar_unlocked _getchar_nolock #define putchar_unlocked _putchar_nolock #elif defined(__GNUC__) #else #define getchar_unlocked getchar #define putchar_unlocked putchar #endif namespace { #define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E) class MaiScanner { public: template void input_integer(T& var) noexcept { var = 0; T sign = 1; int cc = getchar_unlocked(); for (; cc < '0' || '9' < cc; cc = getchar_unlocked()) if (cc == '-') sign = -1; for (; '0' <= cc && cc <= '9'; cc = getchar_unlocked()) var = (var << 3) + (var << 1) + cc - '0'; var = var * sign; } inline int c() noexcept { return getchar_unlocked(); } inline MaiScanner& operator>>(int& var) noexcept { input_integer(var); return *this; } inline MaiScanner& operator>>(long long& var) noexcept { input_integer(var); return *this; } inline MaiScanner& operator>>(string& var) { int cc = getchar_unlocked(); for (; !isvisiblechar(cc); cc = getchar_unlocked()); for (; isvisiblechar(cc); cc = getchar_unlocked()) var.push_back(cc); return *this; } template inline void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; } }; class MaiPrinter { public: template void output_integer(T var) noexcept { if (var == 0) { putchar_unlocked('0'); return; } if (var < 0) putchar_unlocked('-'), var = -var; char stack[32]; int stack_p = 0; while (var) stack[stack_p++] = '0' + (var % 10), var /= 10; while (stack_p) putchar_unlocked(stack[--stack_p]); } inline MaiPrinter& operator<<(char c) noexcept { putchar_unlocked(c); return *this; } inline MaiPrinter& operator<<(int var) noexcept { output_integer(var); return *this; } inline MaiPrinter& operator<<(long long var) noexcept { output_integer(var); return *this; } inline MaiPrinter& operator<<(char* str_p) noexcept { while (*str_p) putchar_unlocked(*(str_p++)); return *this; } inline MaiPrinter& operator<<(const string& str) { const char* p = str.c_str(); const char* l = p + str.size(); while (p < l) putchar_unlocked(*p++); return *this; } template void join(IT begin, IT end, char sep = ' ') { for (bool b = 0; begin != end; ++begin, b = 1) b ? *this << sep << *begin : *this << *begin; } }; } MaiScanner scanner; MaiPrinter printer; class Graph { public: size_t n; vector> vertex_to; Graph(size_t n = 1) :n(n), vertex_to(n) {} inline size_t size() const { return n; } void resize(size_t _n) { vertex_to.resize(n = _n); } void connect(int from, int to) { vertex_to[(size_t)from].emplace_back(to); vertex_to[(size_t)to].emplace_back(from); } }; int N, M; Graph graph; int dp[100010][2]; int dfs(int idx, int from, bool able) { if (dp[idx][able]) return dp[idx][able]; int best = 0; // unselect for (auto nxt : graph.vertex_to[idx]) { if (nxt == from) continue; best += dfs(nxt, idx, 1); } if (able) { int b = 1; for (auto nxt : graph.vertex_to[idx]) { if (nxt == from) continue; b += dfs(nxt, idx, 0); } chmax(best, b); } return dp[idx][able] = best; } int main() { scanner >> N; M = N - 1; graph = Graph(N); repeat(i, M) { int u, v; scanner >> u >> v; --u; --v; graph.connect(u, v); } cout << dfs(rand(0, N-1), -1, 1) << endl; return 0; }