swift, 216 bytes

Result

AC

Duration

871ms

Code [DL]

var x:[Int]=[]
for _ in 0..<4{x+=readLine()!.characters.split{$0==" "}.map{Int(String($0))!}}
for i in 0..<9{x[i]-=x[9+i%3]}
print((x[0]*(x[5]*x[7]-x[4]*x[8])+x[1]*(x[3]*x[8]-x[5]*x[6])+x[2]*(x[4]*x[6]-x[3]*x[7]))/6)

stdin

57 35 21
01 01 69
78 94 59
36 70 68

stdout

12439

stderr

/tmp/code.swift:2:31: warning: 'characters' is deprecated: Please use String or Substring directly
for _ in 0..<4{x+=readLine()!.characters.split{$0==" "}.map{Int(String($0))!}}
                              ^
/tmp/code.swift:2:65: warning: 'init' is deprecated: Please use String or Substring directly
for _ in 0..<4{x+=readLine()!.characters.split{$0==" "}.map{Int(String($0))!}}
                                                                ^

strace