using namespace std;

class mVect
{
    private:
        // NO PRIVATE DATA
    public:
        double i, j, k;
        mVect();
        mVect(string); // NEEDS EXTRA LIBRARIES
        mVect(double,double);
        mVect(double,double,double);
        mVect operator + (mVect);
        mVect operator - (mVect);
        mVect operator = (mVect);
        mVect operator = (string); // NEEDS EXTRA LIBRARIES
        mVect operator / (mVect);
        double operator % (mVect);
        double operator ^ (mVect);
        mVect operator * (double);
        mVect operator / (double);
        mVect operator * (mVect);
        double mod();
        mVect unit();
        void print(); // NEEDS EXTRA LIBRARIES
};

// INITIALIZE EMPTY VECTOR
mVect::mVect()
{
    i=0;
    j=0;
    k=0;
}

// OUTPUT THE VECTOR IN THE FORM [i,j,k]
void mVect::print()
{
    cout << "[" <<  i << "," << j << "," << k << "]";
}

// INITIALIZE VECTOR FROM A String  IN THE FORM [i,j,k]
mVect::mVect(String  v)
{
    size_t p[2]={1,1}, found;
    while (v[p[1]]!=',')
        p[1]++;
    stringstream(v.substr(p[0],p[1]-p[0])) >> i;
    p[0]=++p[1];
    while (v[p[1]]!=',' && v[p[1]]!=']')
        p[1]++;
    stringstream(v.substr(p[0],p[1]-p[0])) >> j;
    if (v[p[1]]==']')
        k=0;
    else
    {
        p[0]=++p[1];
        while (v[p[1]]!=']')
            p[1]++;
        stringstream(v.substr(p[0],p[1]-p[0])) >> k;
    }
}

// INITIALIZE 2D VECTOR
mVect::mVect(double a, double b)
{
    i=a;
    j=b;
    k=0;
}

// INITIALIZE 3D VECTOR
mVect::mVect(double a, double b, double c)
{
    i=a;
    j=b;
    k=c;
}

// ADD TWO VECTORS TOGETHER
mVect mVect::operator + (mVect param)
{
    mVect c;
    c.i=i+param.i;
    c.j=j+param.j;
    c.k=k+param.k;
    return (c);
}

// SUBTRACT ONE VECTOR FROM ANOTHER
mVect mVect::operator - (mVect param)
{
    mVect c;
    c.i=i-param.i;
    c.j=j-param.j;
    c.k=k-param.k;
    return (c);
}

// SET A VECTOR TO ANOTHER VECTOR
mVect mVect::operator = (mVect param)
{
    i=param.i;
    j=param.j;
    k=param.k;
    return *this;
}

// SET A VECTOR TO A String  IN THE FORM [i,j,k]
mVect mVect::operator = (String  v)
{
    mVect temp(v);
    *this = temp;
    return temp;
}

// CROSS PRODUCT
mVect mVect::operator / (mVect param)
{
    mVect c;
    c.i=j*param.k-k*param.j;
    c.j=k*param.i-i*param.k;
    c.k=i*param.j-j*param.i;
    return (c);
}

// DOT PRODUCT
double mVect::operator % (mVect param)
{
    return (i*param.i+j*param.j+k*param.k);
}

// ANGLE BETWEEN IN RADIANS
double mVect::operator ^ (mVect b)
{
    mVect a=*this;
    return (acos((a%b)/(a.mod()*b.mod())));
}

// MULTIPLY BY REAL
mVect mVect::operator * (double b)
{
    mVect c;
    c.i=i*b;
    c.j=j*b;
    c.k=k*b;
    return (c);
}

// DIVIDE BY REAL
mVect mVect::operator / (double b)
{
    mVect c;
    c.i=i/b;
    c.j=j/b;
    c.k=k/b;
    return (c);
}

// STRETCH VECTORS
mVect mVect::operator * (mVect b)
{
    mVect c;
    c.i=i*b.i;
    c.j=j*b.j;
    c.k=k*b.k;
    return (c);
}

// MODULUS
double mVect::mod()
{
    return sqrt(pow(i,2)+pow(j,2)+pow(k,2));
}

// UNIT VECTOR
mVect mVect::unit()
{
    mVect c;
    c.i=i/this->mod();
    c.j=j/this->mod();
    c.k=k/this->mod();
    return c;
}