Example: Please write C a program that opens a.txt which already exists and contains five 2-digit-numbers, and copies these numbers to b.txt, but with increasing order (smallest number first, largest number at the last position)! You should use a user-defined function as well!

Example:
a.txt="1166234587" (It means: 11, 66, 23, 45 and 87.)
After executing the program:
b.txt="1123456687"

I am a student and ı am trying to figure out this problem. I can write all the numbers from one to other but ı cant sort them 2 by 2. Can someone please help me?