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;

class Program
{
	static void Main(string[] args)
	{

        List<int> a = new List<int>();
        List<int> b = new List<int>();

        //string[] s = Console.ReadLine().Split(' ');

        // int a = int.Parse(Console.ReadLine());

        while(true)
        {
            string[] s = Console.ReadLine().Split(' ');

            int c = int.Parse(s[0]);
			int d = int.Parse(s[1]);

            if(c==0&&d==0)
            {
                break;
            }
            else
            {
                if(c>d)
                {
                    int tmp = c;
                    c = d;
                    d = tmp;
                }
				a.Add(c);
				b.Add(d);
            }

        }

        for (int i = 0; i < a.Count;i++)
        {
            Console.WriteLine("{0} {1}",a[i],b[i]);
        }

		//Console.WriteLine("");


	}
}