#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;
}
