by@kurgm
AC
485ms
read j k l read a b c read d e f read g h i echo $[a-=j,b-=k,c-=l,d-=j,e-=k,f-=l,g-=j,h-=k,i-=l,(a*e*i+b*f*g+c*d*h-a*h*f-b*i*d-c*g*e)/6]
35 87 43 22 27 05 41 10 34 27 81 81
12146