func_code_string: #include <bits/stdc++.h>   using namespace std;   long long inf = 1e9 + 7;   long long mod = 998244353;   using namespace std;   vector<long long> g[200005];   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     long long T, N, i, j, k, L, l, m, n;     long long s;     cin >> N >> s;     for (i = 0; i < N - 1; i++) {       long long u, v;       cin >> u >> v;       u--;       v--;       g[u].push_back(v);       g[v].push_back(u);     }     long double ans = 0.0;     if (N == 2)       ans = (long double)s / 2.0;     else {       long long cnt = 0;       for (i = 0; i < N; i++) {         if (g[i].size() == 1) cnt++;       }       ans = (long double)s / (long double)cnt;     }     printf( %.12Lf n , 2 * ans);   }   