#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n;
  k = n;
  double p = 0;
  for (int i = 1; i <= k; i++) {
    p += 1 / float(i);
  }
  cout << fixed << setprecision(12) << p;
  return 0;
}
