gtin = "1324562"
sum = 0
counter = 0
for i in gtin:
    counter = counter + 1
    if counter % 2 != 0:
        sum = sum + int(i) * 3
    else:
        sum = sum + int(i) * 1

print(sum)
lastdigit = 50 - sum
print("8th digit ", lastdigit)

print("Full 7 digit number ", gtin)
print("Full 8 digit number ", str(gtin+str(lastdigit)) )