csharp, 279 bytes

Result

WA

Duration

571ms

Code [DL]

using System;using System.Linq;class A{static void Main(){char[]c={' ','\n'};int[]a=Console.In.ReadToEnd().Split(c).Take(12).Select(Int32.Parse).ToArray();int s=0,1=0;for(int z=8;z-->0;)a[z%9]-=a[9+z%3],s+=a[z%3]*=a[p=3+(z+1)%3]*a[q=6+(z+2)%3]-a[q-3]*a[p+3];Console.Write(s/6);}}

stdin

95 96 07
41 64 87
02 07 16
68 39 35

stdout

Compilation failed: 2 error(s), 0 warnings

stderr

/tmp/code.cs(1,163): error CS1001: Unexpected symbol `1', expecting identifier
/tmp/code.cs(1,202): error CS1525: Unexpected symbol `,', expecting `;' or `}'
Cannot open assembly '/tmp/code.exe': No such file or directory.
rm: can't remove '/tmp/code.exe': No such file or directory

strace