/**
 * CCN2239 Data Structures Assignment 1
 * Ho Yuk Fung 17011817A (103-15)
 * Last edited on: 19/9/2018
 */

import java.util.Scanner;

public class Q2 {

    //declared and initialized a string and integer number
    private static String inputNumber;//declared and initialized
    private static int number = 0;

    //a method that user input the decimal number and check the user input a integer
    public static int getInput() {
        Scanner input = new Scanner(System.in);
        boolean integer = false;
        do {
            System.out.print("Enter a positive integer : ");
            inputNumber = input.nextLine();
            try {
                Integer.parseInt(inputNumber);

                if (Integer.parseInt(inputNumber) >= 0) {
                    number = Integer.parseInt(inputNumber);
                    integer = true;
                }
            } catch (NumberFormatException ex) {
                System.out.println("It is not a positive integer.\nPlease enter a positive integer.\n");//input is a invalid integer

            }
        } while (integer == false);
        return number;
    }

    // a function that the user to change integer number to binary
    public static String intToBin(int number) {
        if (number > 1) {
            return intToBin(number / 2) + number % 2;
        } else
            return number + "";

    }

    //main method
    public static void main(String[] args) {
        getInput();
        System.out.println(intToBin(number));
    }
}