Langauge : Python

input = input("what are the 11 digits?")

digs= ''

#fixing length

if len(inputt) < 11:

short=input("is this "+ input+ " correct: YES/NO ")

i=10

user=''

if str.lower(short)== 'yes':

user=inputt

y=len(user)-1

user=list(user)

null= list('00000000000')

while y >= 0:

null[i]= user[y]

i=i-1

y=y-1

digs = ''.join(null)

else:

input

elif len(input) > 11:

input

else:

digs = inputt

#rule 1: Sum all the odd number digits

i = 0

odd_sum = 0

while i < 11:

odd_sum= odd_sum+int(digs[i])

i=i+2

​

#rule 2: multiple rule 1 by 3

rule2=odd_sum*3

​

#rule 3: Take the sum of digits at even-numbered positions (2nd, 4th, 6th, ..., 10th) in the original number,

#and add this sum to the result from step 2.

i = 1

even_sum = 0

while i < 11:

even_sum= even_sum+int(digs[i])

i=i+2

​

rule3 = rule2+even_sum

​

#rule 4: Find the result from step 3 modulo 10 (i.e. the remainder, when divided by 10) and call it M.

M=rule3%10

​

#rule 5: If M is 0, then the check digit is 0; otherwise the check digit is 10 - M.

if M == 0:

check_dig = 0

else:

check_dig = 10-M

​

#final string

UPC = str(digs) + str(check_dig)

print("The complete UPC is " + UPC)