func_code_string: #include <bits/stdc++.h>   using namespace std;   int main(int argc, char const *argv[]) {     long long n;     cin >> n;     vector<long long> a(n);     for (int i = 0; i < n - 1; ++i) {       long long u, v;       cin >> u >> v;       a[u - 1]++;       a[v - 1]++;     }     for (int i = 0; i < n; ++i) {       if (a[i] == 2) return cout <<  NO , 0;     }     cout <<  YES ;     return 0;   }   