[Codility] Distinct

A가 empty라면 왜 0을 리턴해야 할까?

def solution(A):
    n  = len(A)
    A.sort()
    result = 1

    if n>0:
        for n in range(1,len(A)):
            if A[n-1] != A[n] :
                result +=1
        return result

    else :
        return