func_code_string: #include <bits/stdc++.h>   using namespace std;   const double eps = 1e-6;   const int INF = 0x3f3f3f3f, N = 2000005, M = 2000005, MOD = 1e9 + 7;   int sgn(double x) { return x < -eps ? -1 : (x < eps ? 0 : 1); }   int Rand(int x) { return rand() * rand() % x + 1; }   vector<int> G[N];   int dep[N];   double ans = 0;   void dfs(int x, int _fa, int _dep) {     dep[x] = _dep;     ans += 1. / dep[x];     for (auto v : G[x])       if (v != _fa) {         dfs(v, x, _dep + 1);       }   }   int Solve() {     int n;     cin >> n;     for (int i = 1; i < n; i++) {       int u, v;       cin >> u >> v;       G[u].push_back(v), G[v].push_back(u);     }     dfs(1, 0, 1);     cout << fixed << setprecision(12) << ans << endl;     return 0;   }   void Pre() {}   int main() {     ios::sync_with_stdio(false);     cin.tie(0), cout.tie(0);     Pre();     while (Solve())       ;     return 0;   }   