Task: Text Categorization
Input (English): Text:  The Avia BH-23 was a prototype night fighter aircraft built in Czechoslovakia in 1926. The design was derived from the BH-21 day fighter incorporating the structural changes made in the BH-22 trainer and the type was originally designated BH-22N. Searchlights and other night-flying equipment were added but the Czechoslovak Air Force were not interested in the project and no sale resulted.
Output (English): 6