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 C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;

public class DateSet
{
    //0?????\????????§??°????????????????????????????????????
    static void Main(string[] args)
    {
        /*---??£?¨???¨---*/
        int i = 0;
        int k;
        string[] unit_num;
        List<string> list = new List<string>(); //??\???????????????????????????????????????????????????
        int[] sort_set = new int[2];  //???????????????????????????????????????????????????
        /*---??£?¨???¨---*/

        /*[0 0]?????\????????§???????????????????????????*/
        while (true){

            list.Add((Console.ReadLine()));
            if (list[i] == "0 0"){
                break;
            }
            i++;
        }

        /*????????????????????????x??¨y??????????????¨???*/
        for (k = 0; k < i; k++) {
            /*2?????????????????????????????§??????*/
            unit_num = list[k].Split(' ');
            sort_set[0] = int.Parse(unit_num[0]);
            sort_set[1] = int.Parse(unit_num[1]);

            /*??????????????????????????????????????????*/
            Array.Sort(sort_set);

            Console.WriteLine("{0} {1}", sort_set[0], sort_set[1]);
        }
    }
}