def get_set_vertices(g_or_n):
    """Get number of vertices from the graph, or just pass n itself
    Return set of graph vertices, V = {1, 2,...n}
    """

    if isinstance(g_or_n, int):
        n = g_or_n
    else:
        g = g_or_n
        n = len(g.vs)

    V = list(range(1, n+1))

    return V, n