data={

"北京":{
"昌平":{
"沙河":["old boy","test"],"天通苑":["链家地产","我爱我家"]},\
            "朝阳":{
"望京":["奔驰","默默"],"国贸":["CICC","HP"],"东直门":["advent","飞信"]},\
            "海淀":{}
            }}
print(data)
exit_flag = False
while not exit_flag:
    for i in data:
        print(i)
    choice = input("请选择输入1>>:")
    if choice in data:
        while not exit_flag:
            for i2 in data[choice]:
                print("\t", i2)
            choice2 = input("请选择输入2>>:")
            if choice2 in data[choice]:
                while not exit_flag:
                    for i3 in data[choice][choice2]:
                        print("\t\t", i3)
                    choice3 = input("请选择输入3>>:")
                    if choice3 in data[choice][choice2]:
                        for i4 in data[choice][choice2][choice3]:
                            print("\t\t", i4)
                        choice4 = input("最后一层目录，请按b返回>>:")
                        if choice4 == "b":
                            pass
                        elif choice4 == "q":
                            exit_flag = True
                    if choice3 == "b":
                        break
                    elif choice3 == "q":
                        exit_flag = True
            if choice2 == "b":
                break
            elif choice2 == "q":
                exit_flag == True