Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: CPA-laser effect and exceptional points in PT-symmetric multilayer
  structures
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ