#include <bits/stdc++.h>   using namespace std;   int main() {     std::ios::sync_with_stdio(false);     int n, c = 0, fl, i, a, b;     int deg[100005] = {0};     vector<int> v;     cin >> n;     for (i = 0; i < n - 1; i++) {       cin >> a >> b;       deg[a]++;       deg[b]++;     }     for (i = 1; i < n + 1; i++) {       if (deg[i] > 2) {         c++;         fl = i;       }       if (deg[i] == 1) {         v.push_back(i);       }     }     if (c > 1) {       cout <<  No  << endl;       return 0;     }     cout <<  Yes  << endl;     if (n == 2) {       cout << 1 << endl;       cout << 1 <<     << 2 << endl;     } else {       if (c == 0) {         cout << 1 << endl;         cout << v[0] <<     << v[1] << endl;       } else {         cout << v.size() << endl;         for (i = 0; i < v.size(); i++) {           cout << v[i] <<     << fl << endl;         }       }     }   }   