#include<bits/stdc++.h>
using namespace std;
int main()
{
int n,i=1;
float s=0;
	cin>>n;
	while(i<=n){
		s=s+1.0/i;
		i++;
	}
	printf("%.3f",s);
return 0;
}
/**************************************************************
	Problem: 1014
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/