Problem:
Swapping Two Numbers

Write a program which reads two integers x and y, and prints them in ascending order.

Input

The input consists of multiple datasets. Each dataset consists of two integers x and y separated by a single space.

The input ends with two 0 (when both x and y are zero). Your program should not process for these terminal symbols.

Output

For each dataset, print x and y in ascending order in a line. Put a single space between x and y.

Constraints

0 ≤ x, y ≤ 10000

the number of datasets ≤ 3000

Sample Input

3 2
2 2
5 3
0 0

Sample Output

2 3
2 2
3 5

Solution in JAVA (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * Created by khrom on 2017/06/12.
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        List<String> numList = new ArrayList<>();
        while (true) {
            String x = scanner.next();
            String y = scanner.next();
            if (x.equals("0") && y.equals("0")) {
                break;
            } else {
                numList.add(y + " " + x);
            }
        }
        numList.forEach(s -> System.out.println(s));
    }
}