Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Star Clusters in M31: II. Old Cluster Metallicities and Ages from
  Hectospec Data
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga