crystal, 112 bytes

Result

WA

Duration

498ms

Code [DL]

Y=`dd`.split;r,_,_,a,b,c,d,e,f,g,h,i=Y.map{|e|i+=1;e.to_i-Y[i%3].to_i};p (a*e*i+b*f*g+c*d*h-a*h*f-b*i*d-c*g*e)/6

stdin

08 03 37
05 31 90
74 45 73
15 94 73

stdout

stderr

Syntax error in /volume/CODE:1: can't use variable name 'i' inside assignment to variable 'i'

Y=`dd`.split;r,_,_,a,b,c,d,e,f,g,h,i=Y.map{|e|i+=1;e.to_i-Y[i%3].to_i};p (a*e*i+b*f*g+c*d*h-a*h*f-b*i*d-c*g*e)/6
                                              ^

strace