func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   ll MOD = 1000000007;   ll INF = 1LL << 60;   int main() {     ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);     int n;     cin >> n;     vector<int> tree[n + 1];     int u, v;     for (int i = 0; i < n - 1; i++) {       cin >> u >> v;       tree[u].push_back(v);       tree[v].push_back(u);     }     bool ans = true;     for (int i = 1; i <= n; i++) {       if (tree[i].size() == 2) {         ans = false;         break;       }     }     cout << (ans ?  YES  :  NO ) <<   n ;   }   