#include <iostream>
#include <math.h>

using namespace std;

struct koord
{
    double x,y;
};

void kiir(koord a)
{
    cout << "[" << a.x << "; " << a.y << "]" << endl;
}

koord olvas(istream &be)
{
    koord a;
    be >> a.x >> a.y;
    return a;
}

double tavolsag(koord a)
{
    return sqrt(a.x*a.x + a.y*a.y);
}

koord felez(koord a)
{
    a.x /= 2;
    a.y /= 2;
    return a;
}

int main()
{
    koord pont;
    cout << "Adja meg a vektor koordinatait: ";
    pont = olvas(cin);
    cout << "v = ";
    kiir(pont);
    cout << "|v| = " << tavolsag(pont) << endl;
    cout << "1/2*v = ";
    kiir(felez(pont));
    return 0;
}