Problem statement: Sort a given array by dividing it into 4 subarrays, concurrently sorting each and merging them into one sorted aray. The program should prompt the user to input a series of integers. Each goroutine which sorts ¼ of the array should print the subarray that it will sort. When sorting is complete, the main goroutine should print the entire sorted list.
Solution using 4 goroutines running bubble sort on each of the subarrays, wait group to wait for goroutines to finish and custom merge with a particular counter type implemented.