d-dmd, 184 bytes

Result

WA

Duration

1232ms

Code [DL]

import std.stdio;void main(){int[30]a;for(int i;readf("%d",&a[i]);)a[i]-=a[i%3]*(i++>2);write=(a[3]*(a[7]*a[11]-a[8]*a[10])+a[4]*(a[8]*a[9]-a[11]*a[6])+a[5]*(a[10]*a[6]-a[7]*a[9]))/6;}

stdin

47 85 86
34 24 23
06 41 74
03 92 03

stdout

stderr

std.conv.ConvException@/usr/include/dmd/phobos/std/conv.d(2253): Unexpected ' ' when converting from type LockingTextReader to type int
----------------
??:? int std.conv.parse!(int, std.stdio.LockingTextReader).parse(ref std.stdio.LockingTextReader) [0x43d447]
??:? int std.conv.parse!(int, std.stdio.LockingTextReader).parse(ref std.stdio.LockingTextReader, uint) [0x43d146]
??:? int std.format.unformatValueImpl!(int, std.stdio.LockingTextReader, char).unformatValueImpl(ref std.stdio.LockingTextReader, ref const(std.format.FormatSpec!(char).FormatSpec)) [0x43ca06]
??:? int std.format.unformatValue!(int, std.stdio.LockingTextReader, char).unformatValue(ref std.stdio.LockingTextReader, ref const(std.format.FormatSpec!(char).FormatSpec)) [0x43c90c]
??:? uint std.format.formattedRead!(std.stdio.LockingTextReader, char, int*).formattedRead(ref std.stdio.LockingTextReader, const(char)[], ref int*) [0x439534]
??:? uint std.stdio.File.readf!(int*).readf(const(char[]), ref int*) [0x439483]
??:? uint std.stdio.readf!(int*).readf(const(char[]), int*) [0x4393e0]
??:? _Dmain [0x4392d9]

strace