Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A cautionary tale of interpreting O-C diagrams: period instability in a
  classical RR Lyr Star Z CVn mimicking as a distant companion
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat