number is even or odd in assembly language programming

[org 0x100]

mov ax,9
mov cx,0

begin:
mov dx,0
cmp ax,1
je endk
mov bx,ax
jmp work

odd:
mov bx,3
mul bx
add ax,1
add cx,1
jmp begin

evan:
mov ax,dx
add cx,1
jmp begin


work:
add dx,1
sub bx,2
jz evan
js odd
jmp work



endk:
mov ax,0x4c00
int 0x21