#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
int size = 10000000;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  vector<double> v(n, 0);
  v[0] = 1;
  for (int i = 1; i < n; i++) v[i] = (double)v[i - 1] + (double)1 / (i + 1);
  cout << v[n - 1] << endl;
  return 0;
}
