#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;
    } 
    printf("%.4f",s);
} #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;
    } 
    printf("%.4f",s);
} 
/**************************************************************
	Problem: 1521
	User: linmiaoling
	Language: C++
	Result: Compile Error
****************************************************************/