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: "on profitability of trailing mining"
  Abstract: We compute the revenue ratio of the Trail Stubborn mining strategy in the Bitcoin network and compare its profitability to other block-withholding strategies. We use for this martingale techniques and a classical analysis of the hiker problem. In this strategy the attacker could find himself mining in a shorter fork, but we prove that for some parameter values it is still profitable to not give up. This confirms previous numerical studies.

Connected through hyperedge HE-1 (induced by source paper "on profitability of nakamoto double spend"):
  with members:
    - "profitable double spending attacks"
    - "on profitability of selfish mining"
    - "on profitability of stubborn mining"
    - "double spend races"
    - "an analysis of attacks on blockchain consensus"
    - "analysis of hashrate based double spending"

Connected through hyperedge HE-2 (induced by source paper "selfish mining in ethereum"):
  with members:
    - "selfish mining in ethereum"
    - "bitcoin selfish mining and dyck words"
    - "selfish mining and dyck words in bitcoin and ethereum networks"
    - "on profitability of selfish mining"
    - "the impact of uncle rewards on selfish mining in ethereum"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-3 (induced by source paper "bitcoin selfish mining and dyck words"):
  with members:
    - "on profitability of selfish mining"
    - "on profitability of stubborn mining"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-4 (induced by source paper "selfish mining and dyck words in bitcoin and ethereum networks"):
  with members:
    - "selfish mining in ethereum"
    - "on profitability of selfish mining"
    - "on profitability of stubborn mining"

Connected through hyperedge HE-5 (induced by source paper "on profitability of selfish mining"):
  with members:
    - "on profitability of stubborn mining"
    - "double spend races"
    - "majority is not enough bitcoin mining is vulnerable"

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)