Write an EXE program that accepts a string from the keyboard, converts it to HEX (this

algorithm should also check to see if the input is a number), and stores it. It should take a second

string and convert it to HEX, then add the two numbers, convert it back to ASCII, and output the

result. The program must be able to handle 24-bit numbers (unsigned 0 to 16777215), check for

addition overflow, check for input errors. The A2H and H2A algorithms should be written in

their own procedures (named A2H and H2A). Each INT 21h call should be handled in the file

DOS.MAC with macro names of GetC mychar (get character), GetS mystring (get string), PrintC

mychar (print character), PrintS mystring (print string).