#include //#include //using namespace atcoder; #pragma GCC target ("avx") #pragma GCC optimization ("O3") #pragma GCC optimization ("unroll-loops") using namespace std; typedef vector VI; typedef vector VVI; typedef vector VS; typedef pair PII; typedef pair pii; typedef pair PLL; typedef pair TIII; typedef long long ll; typedef long double ld; typedef unsigned long long ull; #define FOR(i, s, n) for (int i = s; i < (int)n; ++i) #define REP(i, n) FOR(i, 0, n) #define rep(i, a, b) for (int i = a; i < (b); ++i) #define trav(a, x) for (auto &a : x) #define all(x) x.begin(), x.end() #define MOD 1000000007 template inline bool chmax(T1 &a, T2 b) {if (a < b) {a = b; return true;} return false;} template inline bool chmin(T1 &a, T2 b) {if (a > b) {a = b; return true;} return false;} const double EPS = 1e-6, PI = acos(-1); const double pi = 3.141592653589793238462643383279; //ここから編集 typedef string::const_iterator State; ll GCD(ll a, ll b){ return (b==0)?a:GCD(b, a%b); } ll LCM(ll a, ll b){ return a/GCD(a, b) * b; } template< int mod > struct ModInt { int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p) { if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int) (1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const { int a = x, b = mod, u = 1, v = 0, t; while(b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return ModInt(u); } ModInt pow(int64_t n) const { ModInt ret(1), mul(x); while(n > 0) { if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt< mod >(t); return (is); } static int get_mod() { return mod; } }; using modint = ModInt< 1000000007 >; template< typename T > struct Combination { vector< T > _fact, _rfact, _inv; Combination(int sz) : _fact(sz + 1), _rfact(sz + 1), _inv(sz + 1) { _fact[0] = _rfact[sz] = _inv[0] = 1; for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i; _rfact[sz] /= _fact[sz]; for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1); for(int i = 1; i <= sz; i++) _inv[i] = _rfact[i] * _fact[i - 1]; } inline T fact(int k) const { return _fact[k]; } inline T rfact(int k) const { return _rfact[k]; } inline T inv(int k) const { return _inv[k]; } T P(int n, int r) const { if(r < 0 || n < r) return 0; return fact(n) * rfact(n - r); } T C(int p, int q) const { if(q < 0 || p < q) return 0; return fact(p) * rfact(q) * rfact(p - q); } T H(int n, int r) const { if(n < 0 || r < 0) return (0); return r == 0 ? 1 : C(n + r - 1, r); } }; int modpow(ll x, ll n, int mod) { if(x == 0) return 0; ll res = 1; while(n) { if(n&1) res = res*x % mod; x = x*x%mod; n >>= 1; } return res; } int main() { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(7); int n; cin >> n; vector> g(101010); REP(i,n-1) { int a, b; cin >> a >> b; a--; b--; g[a].push_back(b); g[b].push_back(a); } int root = -1; REP(i,n){ if(g[i].size() == 1) { root = i; break; } } vector dist(n, 1e9); dist[root] = 0; queue q; q.push(root); while(q.size()) { int v = q.front(); q.pop(); for(auto u: g[v]) { if(dist[u] > dist[v] + 1) { dist[u] = dist[v] + 1; q.push(u); } } } map mp; REP(i,n) { if(root != i && g[i].size() == 1) { mp[dist[i]]++; } } if(mp.size() == 1) cout << "Yes" << endl; else cout << "No" << endl; return 0; }