[프로그래머스] 폰켓몬

def solution(nums):
    answer = 0
    nums_set = set(nums)
    if len(nums_set) < len(nums)//2:
        answer = len(nums_set)
    else :
        answer = len(nums)//2
    return answer

참고 : https://school.programmers.co.kr/learn/courses/30/lessons/1845?language=python3