#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n;
  while (cin >> n) {
    double sum = 0;
    for (long long int i = n; i > 0; i--) {
      sum += (1.0 / i);
    }
    printf("%.12lf", sum);
    cout << endl;
  }
}
int main() {
  {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
  };
  solve();
  return 0;
}
