#include <bits/stdc++.h>
using namespace std;
int main(){
    float s = 0;
	int i,f = 1,n;
	cin>>n;
	for(i = 1;i <= n;i++){
		s = s + 1.0 * f / i;
		f = f * -1;
	} 
    cout<<fixed<<setprecision(4)<<s<<endl;
} 
/**************************************************************
	Problem: 1521
	User: admin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/