#include <bits/stdc++.h>
using namespace std;
vector<long long> v[100001];
int main() {
  int n;
  cin >> n;
  for (long long i = 1; i < n; i++) {
    long long a, b;
    cin >> a >> b;
    v[a].push_back(b);
    v[b].push_back(a);
  }
  for (long long i = 1; i <= n; i++) {
    if (v[i].size() == 2) {
      cout << "NO";
      return 0;
    }
  }
  cout << "YES";
}
