#include<stdio.h>

void main(){
    double s=0;
    int i,n,f=1;
    scanf("%d",&n);

    for(i=1;i<=n;i++){
        s=s+1.0*f/i;
        f=f*-1;
    }  
    printf("%.4f",s);
}
/**************************************************************
	Problem: 1521
	User: admin
	Language: C
	Result: Accepted
	Time:9 ms
	Memory:1144 kb
****************************************************************/