sqlite3, 489 bytes

Result

AC

Duration

490ms

Code [DL]

with a(a,b,c,d,e,f,g,h,i,j,k,l) as (
select 
substr(v,1,2) as a,
substr(v,4,2) as b,
substr(v,7,2) as c,
substr(v,10,2) as d,
substr(v,13,2) as e,
substr(v,16,2) as f,
substr(v,19,2) as g,
substr(v,22,2) as h,
substr(v,25,2) as i,
substr(v,28,2) as j,
substr(v,31,2) as k,
substr(v,34,2) as l
from i
),
b(m,n,o,p,q,r,s,t,u) as (
select 
d-a as m,
e-b as n,
f-c as o,
g-a as p,
h-b as q,
i-c as r,
j-a as s,
k-b as t,
l-c as u
from a
)
select (m*(q*u-t*r)+n*(r*s-p*u)+o*(p*t-s*q))/6 from b

stdin

50 26 20
52 71 01
54 82 60
72 93 48

stdout

8442

stderr

strace