func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long INF = 1e18;   long long deg[123456];   long long N, S, i, s, e;   long long cnt;   long double ans;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(nullptr);     cin >> N >> S;     for (i = 1; i < N; i++) {       cin >> s >> e;       deg[s - 1]++;       deg[e - 1]++;     }     for (i = 0; i < N; i++)       if (deg[i] == 1) cnt++;     ans = (long double)S * (long double)2 / (long double)cnt;     cout << fixed << setprecision(20) << ans << endl;     return 0;   }   