#include <bits/stdc++.h>
using namespace std;
string digit = "0123456789";
string small = "abcdefghijklmnopqrstuvwxyz";
int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1};
int dy8[] = {1, -1, 1, -1, 0, 0, -1, 1};
int dx4[] = {1, -1, 0, 0};
int dy4[] = {0, 0, 1, -1};
int main() {
  long long n;
  cin >> n;
  long double nn = 0;
  for (long long i = n; i > 0; i--) {
    nn += (1.0 / i);
  }
  cout << setprecision(12);
  cout << fixed;
  cout << nn;
}
