Write sort. c program, it will be run from the command line as follows:
$ ./sort -s 3 -i numbers. txt -o sorted. txt
$ algorithm: merge sort, #integers: 1024, elapsed time: 0s 333ms
sort: name of your program (executable file name)

-s 3: sorting algorithm to use (see below)
-i numbers. txt: input text file, to be sorted by the program
-o sorted. txt: output text file, sorted numbers are saved to this file
sorting algorithms :
0: bubble sort
1: insertion sort
2: selection sort
3: merge sort
4: heapsort
5: quicksort
you should implement these sorting algorithms in your code; you are not
allowed to use the sorting algorithms in any library.