View Code of Problem 71

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int N=scanner.nextInt();
		double a=2,b=1;
		double sum=0;
		for (int i = 0; i < N; i++) {
			sum=sum+a/b;
			double temp=b;
			b=a;
			a=a+temp;
		}
		System.out.printf("%.2f",sum);
	}
	
}