#include <bits/stdc++.h>
using namespace std;
class gfg {
 public:
  double sum(int n) {
    double i, s = 0.0;
    for (i = 1; i <= n; i++) s = s + 1 / i;
    return s;
  }
};
int main() {
  gfg g;
  int n;
  cin >> n;
  cout << g.sum(n);
  return 0;
}
