gistfile1.cpp

struct tochka
{
    float x,y;
};
struct otsechka
{
    tochka m,n
};

float duljina(otsechka a)
{
    return sqrt(pow(a.n.x-a.m.x,2)+(a.n.y-a.m.y,2))
}

int main()
{
    otsechka a;
    cout<<duljina(a);
}