#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n=1,i;
	cin>>n;
	float s=0;
	for(i=1;i<=n;i++)
	{
		s+=1.0/i;
	}
	printf("%.3f",s);
	
	
	

	return 0;
}

/**************************************************************
	Problem: 1014
	User: 21A
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/