#include <bits/stdc++.h>
using namespace std;
int main()
{
int n,t=1;
float sum=0;
cin>>n;

for(int i=1;i<=n;i++){
	sum=sum+(1.0/i)*t;
	t=t*-1;
}
printf("%.4f",sum);
return 0;

}

/**************************************************************
	Problem: 1521
	User: mc002
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/