[Deque]

The code did work, but so what you are saying is that I should use elif instead of if's the whole time?

No, I didn't say that.
I tried to explain that your current checks (if-statements) are inefficient, because you check unnecessarily.
Get to know how if, else and elif work together in order to achieve a better code.
Try to understand by looking at my explanations and pseudocode why it is better.

Maybe I can make up some examples to explain it better. I often feel that my english is not good enough.