Swapping Two Numbers 

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

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.

3 2
2 2
5 3
0 0

2 3
2 2
3 5

0 ≤ x, y ≤ 10000 

the number of datasets ≤ 3000