def activity_selection_finish_time_sorted(start_times, finish_times_sorted):
    """
    Algorithm Paradigmn: Greedy
    Complexity:
        a) Time : O(n)
    Args:
        start_times(list):
        finish_times_sorted(list):

    Returns:
        int: N of activities
    """
    previous_finish_time = 0
    n = 0
    for (start_time, finish_time) in zip(start_times, finish_times_sorted):
        if start_time > previous_finish_time:
            n += 1
            previous_finish_time = finish_time
    return n