kotlin, 614 bytes

Result

WA

Duration

5686ms

Code [DL]

import java.util.Scanner
fun main(args: Array<String>) {
    val input = Scanner(System.`in`)
    var a : Int = input.nextInt()
    var b : Int = input.nextInt()
    var c : Int = input.nextInt()
    var d : Int = input.nextInt()
    var e : Int = input.nextInt()
    var f : Int = input.nextInt()
    var g : Int = input.nextInt()
    var h : Int = input.nextInt()
    var i : Int = input.nextInt()
    var j : Int = input.nextInt()
    var k : Int = input.nextInt()
    var l : Int = input.nextInt()
    d=-a;e=-b;f=-c;
    g=-a;h=-b;i=-c;
    j=-a;k=-b;l=-c;
    print((d*h*l+e*i*j+f*g*k-f*h*j-e*g*l-d*i*k)/6)
}

stdin

20 87 56
03 12 18
22 41 22
16 56 70

stdout

0

stderr

/tmp/code.kt:7:19: warning: variable 'd' initializer is redundant
    var d : Int = input.nextInt()
                  ^
/tmp/code.kt:8:19: warning: variable 'e' initializer is redundant
    var e : Int = input.nextInt()
                  ^
/tmp/code.kt:9:19: warning: variable 'f' initializer is redundant
    var f : Int = input.nextInt()
                  ^
/tmp/code.kt:10:19: warning: variable 'g' initializer is redundant
    var g : Int = input.nextInt()
                  ^
/tmp/code.kt:11:19: warning: variable 'h' initializer is redundant
    var h : Int = input.nextInt()
                  ^
/tmp/code.kt:12:19: warning: variable 'i' initializer is redundant
    var i : Int = input.nextInt()
                  ^
/tmp/code.kt:13:19: warning: variable 'j' initializer is redundant
    var j : Int = input.nextInt()
                  ^
/tmp/code.kt:14:19: warning: variable 'k' initializer is redundant
    var k : Int = input.nextInt()
                  ^
/tmp/code.kt:15:19: warning: variable 'l' initializer is redundant
    var l : Int = input.nextInt()
                  ^

strace