func_code_string: #include <bits/stdc++.h>   using namespace std;   set<int> s;   vector<vector<int> > v;   bool ch[100005];   void go(int i) {     ch[i] = true;     int z = 0;     for (auto it : v[i]) {       if (ch[it] == false) {         z++;         go(it);       }     }     if (z == 0) {       s.insert(i);     }   }   void dynamic() {     int n;     cin >> n;     long double sum = 0;     cin >> sum;     v.resize(n + 1);     memset(ch, 0, sizeof(ch));     for (int i = 0; i < n - 1; i++) {       int x, y;       cin >> x >> y;       v[x].push_back(y);       v[y].push_back(x);     }     go(1);     int z = s.size();     if (v[1].size() == 1) {       z++;     }     sum = sum / z;     sum *= 2;     cout << setprecision(12) << sum <<   n ;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int t;     t = 1;     while (t--) {       dynamic();     }   }   