I am creating a program that would get all the factors of a number(including its negative counterpart) for rational root theorem purposes.

I am successful in getting the positive roots but I can't seem to append the negative roots into my list and it just keeps requiring an input. Here's the code.

```
a = input("Number:")
c = []

for b in (1,a+1):
    if a%b == 0:
       c.append(b)

for d in c:
    e = (-1)*d
    c.append(d)

print c

```

So I tried deleting the "c.append(d)" part and replaced it with "print e". And it printed the negative factors.