def cg_convex_hull(points):
    """Returns the vertices of the convex hull of a set of points in 2D plane."""
    n = len(points)
    if n < 3:
        return []

    # Find leftmost point
    l = 0
    for i in range(1, n):
        if points[i][0] < points[l][0]:
            l = i

    hull = []
    p = l
    q = 0
    while True:
        hull.append(points[p])
        q = (p + 1) % n
        for i in range(n):
            o = orientation(points[p], points[i], points[q])
            if (p != i) and (o == 0 or o == 2):
                q = i
        p = q
        if p == l:
            break

    # Remove intermediate collinear points
    hull.sort()
    leftmost = hull[0]
    rightmost = hull[-1]
    result = [leftmost, rightmost]
    for i in range(n):
        if points[i] == leftmost or points[i] == rightmost:
            continue
        o = orientation(leftmost, points[i], rightmost)
        if o == 1:
            result.append(points[i])

    return result


def orientation(p, q, r):
    """Utility function to find orientation of ordered triplet (p, q, r).
    The function returns the following values:
    0 --> p, q, and r are colinear
    1 --> Clockwise
    2 --> Counterclockwise
    """
    val = (q[1] - p[1]) * (r[0] - q[0]) - (q[0] - p[0]) * (r[1] - q[1])
    if val == 0:
        return 0
    return 1 if val > 0 else 2