Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Metallicity distribution of halo stars and minor merger processes of the
  Galaxy
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ