#include <bits/stdc++.h>
using namespace std;
const char IO_MODE = 3;
inline long long ReadInt() {
  long long x = 0, s = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') s = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return s * x;
}
inline void WriteInt(long long x) {
  char c[20];
  if (!x) {
    putchar('0');
    return;
  }
  if (x < 0) putchar('-'), x = -x;
  int i = 0;
  while (x > 0) c[++i] = x % 10, x /= 10;
  while (i) putchar(c[i--] + 48);
}
template <typename T>
inline void out(T x) {
  if (IO_MODE & 1)
    WriteInt(x);
  else if (typeid(x) == typeid(int))
    printf("%i", x);
  else
    printf("%lld", (long long)x);
}
template <typename T, typename... Args>
inline void out(T x, Args... args) {
  out(x);
  putc(' ', stdout);
  out(args...);
}
template <typename T>
inline void in(T &x) {
  if (IO_MODE & 2)
    x = ReadInt();
  else if (typeid(x) == typeid(int))
    scanf("%i", &x);
  else if (typeid(x) == typeid(long long))
    scanf("%lld", &x);
}
template <typename T, typename... Args>
inline void in(T &x, Args &...args) {
  in(x);
  in(args...);
}
int aa, bb, cc, dd, ee, ff, gg, hh, ii, jj, kk, mm, nn, oo, pp, qq, rr, ss, tt,
    uu, vv, ww, xx, yy, zz;
int tc;
int n;
vector<int> adjList[100100];
double ans;
void dfs(int u, int p, int d) {
  ans += 1.0 / d;
  for (auto v : adjList[u])
    if (v != p) dfs(v, u, d + 1);
}
int main() {
  in(n);
  for (int i = 1; i < n; i++) {
    int u = ReadInt() - 1, v = ReadInt() - 1;
    adjList[u].push_back(v);
    adjList[v].push_back(u);
  }
  dfs(0, 0, 1);
  cout << fixed << setprecision(7) << ans << endl;
}
