Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The metallicity of the old open cluster NGC 6791
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat