Consider the following program segments for two different processes (P1, P2) executing concurrently and where B and A are not shared variables, but X starts at zero as a shared variable.

P1

DO A = 1, 5

X =X - 1

ENDDO

P2

DO B = 1, 4 X =X +1

ENDDO

If the processes P1 and P2 execute concurrently once at any speed, what are the possible resulting final values of x? Explain your answers.