I have a question about the bubble alignment of Python!

def sorting_list(list_a,sorting):
    for i in range(len(list_a)+1):
        for j in range(len(list_a)-i-1):
            if sorting==0:
                if list_a[j+1]>list_a[j]:
                    tmp = list_a[j+1]
                    list_a[j+1] = list_a[j]
                    list_a[j] = tmp
                else:
                    if list_a[j+1]<list_a[j]:
                        tmp = list_a[j+1]
                        list_a[j+1] = list_a[j]
                        list_a[j] = tmp


list_a = [10,9,1,4,8,6,11,12]
list_a = []
tmp = 0
sorting = -1

while True:
    sorting = int('input('alignment ascending order: 0\nalignment descending order: 1\nEnter a number :')
    if sorting == 0 or sorting == 1:
        break;
    else:
        print ("Please re-enter a number")

while True:
    tmp = int (input('Enter a number :')
    if tmp == -1:
        break;
    list_a.append(tmp)

sorting_list(list_a,sorting)

print(list_a)