#include <bits/stdc++.h>
using namespace std;
struct Edge {
  int v, nxt;
} e[500005];
int head[500005], tot;
int dep[500005];
void AddEdge(int u, int v) {
  e[++tot] = {v, head[u]};
  head[u] = tot;
  e[++tot] = {u, head[v]};
  head[v] = tot;
}
void dfs(int x, int f) {
  dep[x] = dep[f] + 1;
  for (int i = head[x]; i; i = e[i].nxt) {
    if (e[i].v == f) continue;
    dfs(e[i].v, x);
  }
}
int main() {
  int n, a, b;
  scanf("%d", &n);
  for (int i = 1; i < n; ++i) {
    scanf("%d%d", &a, &b);
    AddEdge(a, b);
  }
  dep[1] = 1;
  dfs(1, 0);
  double ans = 0.0;
  for (int i = 1; i <= n; ++i) ans += 1.0 / dep[i];
  printf("%.7f", ans);
  return 0;
}
