#  -------------------------------
#  Difficult Rocket
#  Copyright © 2021 by shenjackyuanjie
#  All rights reserved
#  -------------------------------

"""
writen by shenjackyuanjie
mail:   3695888@qq.com
github: @shenjackyuanjie
gitee:  @shenjackyuanjie
"""


class N:
    pass


class m:
    pass


class s:
    pass