Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: Over a 1-year period, rigid ureteroscopy has been used to retrieve ureteric calculi in 120 patients. The technical details, causes of failure and the complications are described. An initial success rate of 78% was obtained. It was concluded that ureteroscopy should replace blind procedures for the extraction of ureteric stones.

Adult