#include <iostream>
using namespace std;
int main()
{
	int n,i=1;
	double c=0;
	cin >> n;
	while(i<=n)
	{
		c = c + 1.0/i;
		i++;
	}
	printf("%.3f",c);
	return 0;
 } 
/**************************************************************
	Problem: 1014
	User: xiaomingze
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/