/*
题目：编写一个函数，输入n为偶数时，调用函数求1/2+1/4+...+1/n,当输入n为奇数时，
调用函数1/1+1/3+...+1/n(利用指针函数)
*/
import java.util.*;
public class Class39 {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("请输入一个数字:");
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
System.out.println(sum(n));
}
public static double sum(int n){
double num = 0;
if(n % 2 == 0){
for(int i = 2; i <= n; i++){
num += (double)1/i;
}
}else{
for(int i = 1; i <= n; i++){
num += (double)1/i;
}
}
return num;
}
}