HELP - display a menu of commands DISPLAY - display the list of numbers PRINT - print a number (FIRST;LAST;nth) SWAP - exchange two elements (nth;mth) ADD - add a number to the list (FIRST;LAST) EXIT - terminate execution of the program >>> display 21 62 68 28 84 33 72 32 53 74 >>> swap 5 2 >>> display 21 84 68 28 62 33 72 32 53 74 >>> exit