Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A cold metal-poor cloud traced by a weak MgII absorption at z~0.45.
  First detection of SiI, CaI and FeI in a QSO absorber
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex