lua, 138 bytes

Result

WA

Duration

491ms

Code [DL]

a={} for i=-3,8 do a[i]=io.read("*n")-a[i%3-3]end
for i=0,2 do b=(i+1)%3 c=(i+2)%3 d=a[i]+a[b+3]+a[c+6] e=a[i]+a[c+3]+a[b+6]end
print(d-e)

stdin

10 84 06
69 15 47
20 96 66
33 45 64

stdout

stderr

/usr/bin/lua5.3: /volume/CODE:1: attempt to perform arithmetic on a nil value (field '?')
stack traceback:
	/volume/CODE:1: in main chunk
	[C]: in ?

strace