#include <bits/stdc++.h>
using namespace std;
vector<vector<int> > arr;
double ans = 0;
void dfs(int x, int h, int p) {
  ans += 1.0 / h;
  for (int i = 0; i < arr[x].size(); i++) {
    if (arr[x][i] != p) dfs(arr[x][i], h + 1, x);
  }
}
int main() {
  int n;
  cin >> n;
  int x, y;
  arr.resize(n + 1);
  for (int i = 0; i < n - 1; i++) {
    cin >> x >> y;
    arr[x].push_back(y);
    arr[y].push_back(x);
  }
  dfs(1, 1, -1);
  printf("%0.7f", ans);
}
