#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
const int mod = 1e9 + 7;
int n, a, b;
double ans;
vector<vector<int>> g(N);
void dfs(int u, int par, int depth) {
  ans += 1.0 / depth;
  for (auto v : g[u])
    if (v != par) dfs(v, u, depth + 1);
}
int main() {
  cin >> n;
  for (int i = 1; i < n; i++) {
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1, 1, 1);
  cout << fixed << setprecision(9) << ans;
}
