Deleting digits

def main():

    number = input()

    count = 0

    working_number = int(number)
    str_num = list(str(working_number))

    while working_number != 0:

        biggest = 0
        for num in str_num:

            biggest = max(biggest, int(num))

        #print(biggest)

        working_number = int(working_number) - int(biggest)

        #print(working_number)
        str_num = list(str(working_number))

        count += 1

    print(count)



main()

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED