Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned
  Aerial Vehicles
2
The categories of this paper are: math
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat