In ARM Assembly Code please.

2. You have some positive non-zero two's complement number into R0 Write an instruction(s) to change a sign of the number in R0. - Your command(s) should works for any number in R0 - Do not use any other registers! MOV R0, \#5 -- Place your code here! -- Write some other instruction(s) to change a sign of the number in R0 again. - Use some another command(s) to do it - Do not use any other registers! -- Place your code here! -- Check yourself: Do you have your original number in R ? Can you change the sign by using some thrid way? - Do not use any other registers! -- Place your code here