Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Chemical abundances for Hf 2-2, a planetary nebula with the strongest
  known heavy element recombination lines
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org