#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("tune=native")
using namespace std;
const int MAX = 1e5 + 5;
const long long MOD = 1000000007;
const long long MOD2 = 2010405347;
const long long INF = 2e18;
const int dr[] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
const int dc[] = {0, 1, 0, -1, 1, -1, 1, -1, 0};
const double pi = acos(-1);
const double EPS = 1e-9;
const int block = 600;
int n, a, b;
double ans;
vector<int> v[MAX];
void dfs(int nw, int par, int dep) {
  ans += 1.0 / dep;
  for (int i : v[nw])
    if (i != par) dfs(i, nw, dep + 1);
  return;
}
int main() {
  cout << fixed << setprecision(10);
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 2; i <= n; ++i) {
    cin >> a >> b;
    v[a].push_back(b);
    v[b].push_back(a);
  }
  dfs(1, 0, 1);
  cout << ans << '\n';
  return 0;
}
