text: #ifdef _DEBUG
  #include "../../../library/src/debug_template.hpp"
  #define DMP(...) dump(#__VA_ARGS__, __VA_ARGS__)
  #else
  #define DMP(...) ((void)0)
  #endif
  
  #include <cassert>
  #include <cstdio>
  #include <cmath>
  #include <iostream>
  #include <iomanip>
  #include <string>
  #include <vector>
  #include <set>
  #include <map>
  #include <unordered_map>
  #include <queue>
  #include <numeric>
  #include <algorithm>
  #include <bitset>
  #include <variant>
  
  using namespace std;
  using lint = long long;
  constexpr int INF = 1010101010;
  constexpr lint LINF = 1LL << 60;
  
  struct init {
      init() {
          cin.tie(nullptr);
          ios::sync_with_stdio(false);
          cout << fixed << setprecision(10);
      }
  } init_;
  
  int main() {
  
      int N;
      cin >> N;
  
      long double ans = 0;
      for (int i = 1; i < N; i++) {
          ans += 1.0L * N / (N - i);
      }
      
      cout << ans << '\n';
  
      return 0;
  }
  