#include<iostream> 

using namespace std;

int main()
{
	int n;
	cin>>n;
	float sum=0;
	int i=1;
	while(i<=n){
		
		sum+=1.0/i;
		i++;
	}
	
	printf("%.3f",sum);
	
	
	return 0;
}
/**************************************************************
	Problem: 1014
	User: 231308061
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/