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

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