func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int ans = 0;     char ch = getchar();     while (!isdigit(ch)) {       ch = getchar();     }     while (isdigit(ch)) {       ans = (ans << 3) + (ans << 1) + (ch ^ 48), ch = getchar();     }     ans = ans + 0 + 0;     return ans;   }   int first[100005], n, cnt, dep[100005];   double ans = 0;   struct edge {     int v, next;   } e[100005 << 1];   inline void add(int u, int v) {     e[++cnt].v = v, e[cnt].next = first[u], first[u] = cnt;   }   inline void dfs(int p, int fa) {     for (int i = first[p]; i; i = e[i].next) {       int v = e[i].v;       if (v == fa) continue;       dep[v] = dep[p] + 1, dfs(v, p);     }   }   int main() {     n = read();     for (int i = 1; i < n; ++i) {       int u = read(), v = read();       add(u, v), add(v, u);     }     dep[1] = 1, dfs(1, 1);     for (int i = 1; i <= n; ++i) ans += 1.0 / (1.0 * dep[i]);     printf( %.20lf , ans);     return 0;   }   