#include <bits/stdc++.h>
using namespace std;
vector<vector<int> > g;
vector<int> u, rem;
vector<set<int> > mem;
void go(int i, int par = -1) {
  if (g[i].size() > 2) return;
  rem[i] = 1;
  for (int j = 0; j < g[i].size(); j++) {
    if (g[i][j] != par) go(g[i][j], i);
  }
}
int main() {
  int n;
  while (cin >> n) {
    g.clear();
    g.resize(n);
    for (int i = 0; i < n - 1; i++) {
      int x, y;
      scanf("%d %d", &x, &y);
      ;
      g[x - 1].push_back(y - 1);
      g[y - 1].push_back(x - 1);
    }
    u.clear();
    u.resize(n, 0);
    rem = u;
    mem.clear();
    mem.resize(n);
    for (int i = 0; i < n; i++) {
      if (g[i].size() == 1) go(i);
    }
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < g[i].size(); j++) u[i] += rem[g[i][j]];
    }
    bool ok = 1;
    for (int i = 0; i < n && ok; i++) {
      if (!rem[i]) {
        int tmp = 0;
        for (int j = 0; j < g[i].size(); j++) {
          if (g[g[i][j]].size() - min(u[g[i][j]], 2) > 1) tmp++;
        }
        if (tmp > 2) ok = 0;
      }
    }
    ok ? cout << "Yes\n" : cout << "No\n";
  }
  return 0;
}
