#include <bits/stdc++.h>
using namespace std;
long long int n, u, v;
vector<int> arr[100001];
long double ans = 0.0;
long long int siz[100001]{0};
void dfs(int to, int from, int val) {
  int ret = 1;
  ans += 1.0 / val;
  for (auto i : arr[to]) {
    if (i != from) {
      dfs(i, to, val + 1);
      siz[to] += siz[i];
    }
  }
}
void pre() {}
void solve() {
  cin >> n;
  for (int i = 0; i < n - 1; i++) {
    cin >> u >> v;
    arr[u].push_back(v);
    arr[v].push_back(u);
  }
  dfs(1, 0, 1);
  cout << setprecision(26) << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  pre();
  solve();
}
