Working 4bit alu

A is value A
D is value B
F = 1
G = 2
H = 4
J = 8
K switches between add and subtraction. It starts in add mode.
W toggles the output

Input and output is in binary.

Output value cannot be more then 15 or less then 0.

The bottom debuggers are the in put.
The top debuggers are the output.

Numbers in binary:
00=0000
01=1000
02=0100
03=1100
04=0010
05=1010
06=0110
07=1110
08=0001
09=1001
10=0101
11=1101
12=0011
13=1011
14=0111
15=1111