튜플

def solution(s):

    answer = []

    s = s.split('},{')

    s[0] = s[0].replace('{','')

    s[-1] = s[-1].replace('}','')

    #print(s)

    s.sort(key=len)

    for i in s:

        i = i.split(',')

        for j in i:

            if int(j) not in answer:

                answer.append(int(j))

    #print(answer)

    return answer

solution("{{2},{2,1},{2,1,3},{2,1,3,4}}")