#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	double s=0.0;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		s+=1.0/i;
	}
	printf("%.3f",s);
	return 0;
}

/**************************************************************
	Problem: 1014
	User: lzc
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/