python3, 148 bytes

Result

AC

Duration

497ms

Code [DL]

j,k,l,a,b,c,d,e,f,g,h,i=map(int,open(0).read().split())
a-=j
b-=k
c-=l
d-=j
e-=k
f-=l
g-=j
h-=k
i-=l
print((a*e*i+b*f*g+c*d*h-a*h*f-b*i*d-c*g*e)//6)

stdin

28 13 44
52 38 09
43 82 03
94 47 08

stdout

10205

stderr

strace