human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "increasing security in cloud environment"
  Abstract: The concept of cloud computing was introduced to meet the increase in demand for new application for a project, and to provide a large storage facility whenever or wherever a user needs it. The cloud system facility helped many industries as well as individual users to get authentic software at a very low cost. But with this new system comes the major concern of security, as the connection to the cloud is through the web and the data and application availability need to be handled for each client. The paper describes the various security measures that can be added in isolation or in combination for securing data transmission, server and client.

Connected through hyperedge HE-1 (induced by source paper "inter cloud data security strategies"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"
    - "a survey on security issues in cloud computing"
    - "a new trusted and collaborative agent based approach for ensuring cloud security"
    - "grid security and integration with minimal performance degradation"
    - "security scheme for distributed dos in mobile ad hoc networks"
    - "implementation of a cloud data server cds for providing secure service in e business"
    - "a semi distributed reputation based intrusion detection system for mobile adhoc networks"
    - "a brief history of the internet"

Connected through hyperedge HE-2 (induced by source paper "cloud computing an approach with modern cryptography"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"
    - "a semi distributed reputation based intrusion detection system for mobile adhoc networks"
    - "compchall addressing password guessing attacks"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.CR(Cryptography and Security)