func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 1e5 + 10;   vector<int> tree[maxn];   int n;   bool flag[maxn];   double dfs(int deep, int at) {     flag[at] = false;     double ret = 0;     for (int i = 0; i < tree[at].size(); i++) {       int one = tree[at][i];       if (flag[one]) ret += dfs(deep + 1, one);     }     return ret + 1.0 / (deep);   }   int main() {     cin >> n;     for (int i = 0; i < n; i++) flag[i] = true;     for (int i = 0; i < n - 1; i++) {       int a, b;       cin >> a >> b;       a--;       b--;       tree[a].push_back(b);       tree[b].push_back(a);     }     printf( %.9lf , dfs(1, 0));     return 0;   }   