struct Point {
    field x;
    field y;
}

def main(Point p, Point q) -> Point {
    field a = 42;
    field d = 21;

    field dpxpyqxqy = d * p.x * p.y * q.x * q.y;

    return Point {
        x: (p.x * q.y + q.x * p.y) / (1 + dpxpyqxqy),
        y: (q.x * q.y - a * p.x * p.y) / (1 - dpxpyqxqy)
    };
}