csharp, 298 bytes

Result

WA

Duration

529ms

Code [DL]

using System;
string s;
for(int i=4;i>0;i--){
  s+=Console.ReadLine() + " ";
}
int[] a=s.Split(' ').Take(12).Select(Int32.Parse).ToArray();
foreach(int z in Enumerable.Range(0,9)){a[z]-=a[9+z%3];}
Console.Write(-(a[7]*(a[3]*a[2]-a[0]*a[5])+a[6]*(a[1]*a[5]-a[4]*a[2])+a[8]*(a[0]*a[4]-a[3]*a[1]))/6);

stdin

96 65 34
54 49 32
68 09 34
73 21 65

stdout

Compilation failed: 1 error(s), 0 warnings

stderr

/tmp/code.cs(2,0): error CS1525: Unexpected symbol `string'
Cannot open assembly '/tmp/code.exe': No such file or directory.
rm: can't remove '/tmp/code.exe': No such file or directory

strace