package problem_5;
//ComputeFibonacci.java
import java.io.*;

public class ComputeFibonacci {
	public static void main(String[] args){
		try{
			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
			System.out.print("Serial number = ");
			Integer n = Integer.valueOf(br.readLine());		//讀入待求斐波那契數列項序號，首項序號為1
			if(n.compareTo(0) <= 0)
				System.out.println("Invalid input");		//無效序號輸入
			else
				System.out.println("F[" + n.intValue() + "] = " + calculateFibonacci(n.intValue()));
		}
		catch(IOException e){
			System.out.println(e);
		}
	}

	//計算并返回斐波那契數列第n項值
	public static int calculateFibonacci(int n){
		if(n == 1) 
			return 0;
		else if(n == 2)
			return 1;
		else 
			return calculateFibonacci(n - 1) + calculateFibonacci(n - 2);
	}
}