Value num$\_$in is read from input. Write a while loop that iterates until num$\_$in is negative. In each iteration:

Update value output$\_$num as follows:

If num$\_$in is even, subtract num$\_$in from output$\_$num.

Otherwise, add num$\_$in to output$\_$num.

Then, read a value from input as an integer into variable num$\_$in$.$