https://school.programmers.co.kr/learn/courses/30/lessons/12903
def solution(s): if len(s) % 2 == 0: # 짝수 return s[len(s) // 2 - 1: len(s)//2 + 1] return s[len(s)// 2: len(s)// 2 + 1] # 홀수