program has to end but won't stop

Question

I am trying to build a program that controls if a integer is divisible by '9'. I have this for the code.

import sys
a=int(sys.argv[1])

if a < 1:
    pos_num= a*(-1)
    b=map(int, str(pos_num))
    c=sum(b)
    print(c)
else:
    b=map(int, str(a))
    c=sum(b)
    print(c)


if c > 10:
    d=map(int, str(c))
    d1= sum(d)
    print(d1)
elif c==9:
    print("yes")
else:
    print("no")


if d1 > 10:
    e=map(int, str(d1))
    e1= sum(e)
    print(e1)
elif c==9:
    print("yes")
else:
    print("no")


if e1 > 10:
    f=map(int, str(e1))
    f1= sum(f)
    print(d1)
elif c==9:
    print("yes")
else:
    print("no")

The problem is that when the integer isn't big for example '27', the program will display that it doesn't have a value for 'd1'. Does someone have a suggestion?

Answer 1

Replace the entire program with

import sys
print("yes" if ((int(sys.argv[1]) % 9)==0) else "no")