#include <iostream>
#include <sstream>
#include <string>
#include <list>
#include <vector>
#include <queue>
#include <algorithm>
#include <climits>
#include <cstring>
#include <cmath>
#include <stack>
#include <iomanip>
#include <tuple>
#include <functional>
#include <cfloat>
#include <map>
#include <set>
#include <array>
#include <stdio.h>
#include <string.h>
#include <random>
#include <cassert>
using ll = long long;
using ull = unsigned long long;
using uint = unsigned int;
using namespace std;
#define int long long
#define CONTAINS_VEC(v,n) (find((v).begin(), (v).end(), (n)) != (v).end())
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
#define ARY_SORT(a, size) sort((a), (a)+(size))
#define REMOVE(v,a) (v.erase(remove((v).begin(), (v).end(), (a)), (v).end()))
#define REVERSE(v) (reverse((v).begin(), (v).end()))
#define ARY_REVERSE(v,a) (reverse((v), (v)+(a)))
#define REP(i, n) for (int (i)=0; (i) < (n); (i)++)
#define REPE(i, n) for (int (i)=0; (i) <= (n); (i)++)
#define CONTAINS_MAP(m, a) ((m).find((a)) != m.end())
#define CONTAINS_SET(m, a) ((m).find((a)) != m.end())
void YesNo(bool b) { cout << (b ? "Yes" : "No") << endl; exit(0); }
void Yes() { cout << "Yes" << endl; exit(0); }
void No() { cout << "No" << endl; exit(0); }

signed main()
{
	int N;
	cin >> N;

	double ans = 0;
	for (int i = 1; i <= N; i++)
	{
		ans += N * (1 / (double)i);
	}
	cout << fixed << setprecision(10);
	cout << ans - 1 << endl;
}


#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  long double ans = 0;
  for (int i = n - 1; i >= 1; i--) {
    ans += 1 / (long double) i;
  }
  ans *= n;
  cout << fixed << setprecision(17) << ans << '\n';
  return 0;
}

/* stuff you should look for, credit: Benq

* int overflow, array bounds
* special cases (n=1? || n=0? ...)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH

*/
