V of Tetrahedron

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    //Vuvejdat se stoinosti na tochki A, B, C, D v masivi
    int A[3] = { 0,0,1 };
    /*
    cout << "Vuvedete stoinostite na tochka A: " << endl;
    cout << "i: "; cin >> A[0]; cout << "j: "; cin >> A[1];cout << "k: "; cin >> A[2];
    */
    int B[3] = { 2,1,3 };
    /*
    cout << "Vuvedete stoinostite na tochka B: " << endl;
    cout << "i: "; cin >> B[0]; cout << "j: "; cin >> B[1];cout << "k: "; cin >> B[2];
    */
    int C[3] = { -1,0,1 };
    /*
    cout << "Vuvedete stoinostite na tochka C: " << endl;
    cout << "i: "; cin >> C[0]; cout << "j: "; cin >> C[1];cout << "k: "; cin >> C[2];
    */
    int D[3] = { 1,3,2 };
    /*
    cout << "Vuvedete stoinostite na tochka D: " << endl;
    cout << "i: "; cin >> D[0]; cout << "j: "; cin >> D[1];cout << "k: "; cin >> D[2];
    */
    //vector AC
    int AC[3];
    AC[0] = C[0] - A[0];
    AC[1] = C[1] - A[1];
    AC[2] = C[2] - A[2];
    cout << "AC: " << AC[0] << " " << AC[1] << " " << AC[2] << endl;

    //vector AB
    int AB[3];
    AB[0] = B[0] - A[0];
    AB[1] = B[1] - A[1];
    AB[2] = B[2] - A[2];
    cout << "AB: " << AB[0] << " " << AB[1] << " " << AB[2] << endl;

    //vector AD
    int AD[3];
    AD[0] = D[0] - A[0];
    AD[1] = D[1] - A[1];
    AD[2] = D[2] - A[2];
    cout << "AD: " << AD[0] << " " << AD[1] << " " << AD[2] << endl;

    //cross product of AC and AB
    int ACAB[3];
    ACAB[0] = (AC[1] * AB[2]) - (AC[2] * AB[1]);
    ACAB[1] = (AC[0] * AB[2]) - (AC[2] * AB[0]);
    ACAB[2] = (AC[0] * AB[1]) - (AC[1] * AB[0]);
    cout << "ACAB: " << ACAB[0] << " " << ACAB[1] << " " << ACAB[2] << endl;

    //cross product of ACxAB and AD
    int PROD[3];
    PROD[0] = ACAB[0] * AD[0];
    PROD[1] = ACAB[1] * AD[1];
    PROD[2] = ACAB[2] * AD[2];
    cout << "PROD: " << PROD[0] << " " << PROD[1] << " " << PROD[2] << endl;
    int sum_prod = PROD[0] - PROD[1] + PROD[2];
    sum_prod = abs(sum_prod);

   //Namirane na v
    cout << endl;
    cout << "V = " << sum_prod << "/6" << endl;

}

// V = 1/6 (AC x AB) x AD