import java.util.Scanner

val input = Scanner(System.`in`)
fun main(args: Array<String>) {
    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)
}