in ARM assembly for Raspberry Pi. Please provide explanation and output

Write a program to prompt the user for a number, and determine if that number is prime. Your program should print out Number n is prime if the number is prime, and Number n is not prime if the number is not prime. The user should be able to enter input a -1 is entered. It should print an error if 0, 1, 2 or any negative number other than is entered.

Use this set up

.text .global main

main:

#Save return to Os on stack

SUB sp,sp #4

STR lr, [sp,#0]

#Enter program here

#return to the OS

LDR lr, [sp,#0]

ADD sp,sp, #4

MOV pc, lr

.data