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;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ITP1_3_C
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> x = new List<int>();
            List<int> y = new List<int>();
            int temp = 0;

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

                if (int.Parse(input[0]) == 0 && int.Parse(input[1]) == 0) break;

                x.Add(int.Parse(input[0]));
                y.Add(int.Parse(input[1]));
            }

            for (int i=0; i < x.Count; i++)
            {
                if (x[i] > y[i])
                {
                    temp = x[i];
                    x[i] = y[i];
                    y[i] = temp;
                }
            }

            for (int j=0; j < x.Count; j++)
            {
                Console.WriteLine("{0} {1}", x[j], y[j]);
            }

            
        }
    }
}