View Code of Problem 71

import java.util.Scanner;

public class Main
{
  public static void main(String[] args)
  {
    Scanner scan=new Scanner(System.in);
    int n=scan.nextInt();
    double a=1;
    double b=2;
    double k=0.0;
    double sum=0.0;
    for(int i=1;i<=n;i++)
    {
      sum+=b/a;
      k=b;
      b=a+b;
      a=k;
      
    }
    System.out.println(String.format("%.2f",sum));

    
  }
}