Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Tunka Experiment: Towards a 1-km^2 Cherenkov EAS Array in the Tunka
  Valley   The project of an EAS Cherenkov array in the Tunka valley/Siberia with an
area of about 1 km^2 is presented. The new array will have a ten times bigger
area than the existing Tunka-25 array and will permit a detailed study of the
cosmic ray energy spectrum and the mass composition in the energy range from
10^15 to 10^18 eV.

30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math