Mathematics Q#16 in Codekata

Q: In XYZ country there is rule that car’s engine no. depends upon car’ number plate. Engine no is sum of all the integers present on car’s Number plate.The issuing authority has hired you in order to provide engine no. to the cars.Your task is to develop an algorithm which takes input as in form of string(Number plate) and gives back

Engine number.

My code: Number_plate = str(input())

a = int(Number_plate[2:3])

b = int(Number_plate[3:4])

c = int(Number_plate[8:9])

d = int(Number_plate[9:10])

e = int(Number_plate[10:11])

f = int(Number_plate[11:12])

Engine_number = a + b + c + d + e + f

print(Engine_number)

Issue: Failure in test case 2

Private Testcase #2

Testcase Status:

>>> error

Input:

HR06-J-7801

Expected Output:

22

Actual Output:

Traceback (most recent call last):
  File "main.py", line 8, in 
    f = int(Number_plate[11:12])
ValueError: invalid literal for int() with base 10: ''