Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: First observation of the decay $B^0 \rightarrow D^0 \overline{D}{}^0 K^+
  \pi^-$
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys