You will be given a definition of a task first, then some input of the task.
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.

Abstract: The purpose of this paper is to propose a practical classification of mammary hypertrophy and compare perioperative factors in two types of reduction mammaplasty: the Pontes and Robbins techniques. In a series of 51 patients, the advantages and disadvantages of each method are compared and discussed. The Pontes method appears to be better for the low-volume and ptotic (type II and III) breast, whereas the Robbins technique has a more universal application.
Output:
Breast