#include <iostream>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>

using Int = boost::multiprecision::cpp_int;
using Float = boost::multiprecision::cpp_dec_float_100;
using Rational = boost::rational<Int>;

double solve(int k){
	Rational ans = 0;
	for(Int i = 1; i <= k; ++i){
		ans += Rational(1, i);
	}
	ans *= Rational(1, k);
	return boost::rational_cast<double>(ans);
}

double solve2(int k){
	float ans = 0;
	for(int i = 1; i <= k; ++i){
		ans += (float)1 / i;
	}
	ans /= k;
	return ans;
}

bool check(double x, double y){
	if(x - 1e-6 <= y && y <= x + 1e-6) return true;
	if(x * (1 - 1e-6) <= y && y <= x * (1 + 1e-6)) return true;
	return false;
}

int main(){
	int k;
	std::cin >> k;
	if(k == 0) std::cout << "1.6449340" << std::endl;
	else std::cout << solve(k) << std::endl; // setprecision 忘れ
}