#include using namespace std; #define REP(i, n) for(int i=0; i<(n); ++i) #define RREP(i, n) for(int i=(n);i>=0;--i) #define FOR(i, a, n) for (int i=(a); i<(n); ++i) #define RFOR(i, a, b) for(int i=(a);i>=(b);--i) #define SZ(x) ((int)(x).size()) #define ALL(x) (x).begin(),(x).end() #define DUMP(x) cerr<<#x<<" = "<<(x)< ostream &operator<<(ostream &os, const vector &v) { REP(i, SZ(v)) { if (i) os << " "; os << v[i]; } return os; } template void debug(const vector &v) { cout << "["; REP(i, SZ(v)) { if(i) cout << ", "; cout << v[i]; } cout << "]" << endl; } template ostream &operator<<(ostream &os, const pair &p) { return os << p.first << " " << p.second; } template void debug(const pair &p) { cout << "(" << p.first << " " << p.second << ")" << endl; } template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; } using ll = long long; using ull = unsigned long long; using ld = long double; using P = pair; using vi = vector; using vll = vector; using vvi = vector; using vvll = vector; const ll MOD = 1e9 + 7; const ll MOD998 = 998244353; const int INF = INT_MAX; const ll LINF = LLONG_MAX; const int inf = INT_MIN; const ll linf = LLONG_MIN; const ld eps = 1e-9; vector centroid(const vector>& g) { const int n = g.size(); vector sz(n,1), ret; function dfs = [&](int u,int p) { bool isCent = true; for (int v : g[u]) { if (v == p) continue; sz[u] += dfs(v, u); if (sz[v] > n / 2) isCent = false; } if (n - sz[u] > n / 2) isCent = false; if (isCent) ret.emplace_back(u); return sz[u]; }; dfs(0, -1); return ret; } int main() { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(10); int n; cin >> n; vvi g(n); vi d(n); REP(i, n-1) { int a, b; cin >> a >> b; a--; b--; g[a].push_back(b); g[b].push_back(a); d[a]++; d[b]++; } auto c = centroid(g); if(SZ(c) == 2) { cout << (n == 2 ? "Yes" : "No") << endl; } else { vi depth(n); function dfs = [&](int now, int prev, int nowdepth) { depth[now] = nowdepth; for(auto &nxt: g[now]) { if(nxt == prev) continue; dfs(nxt, now, nowdepth+1); } }; dfs(c[0], -1, 0); set st; REP(i, n) { if(d[i] == 1) { st.insert(depth[i]); } } cout << (SZ(st) == 1 ? "Yes" : "No") << endl; } return 0; }