Hi,

Your issue is that you're using input() rather than raw_input(). I'm not sure you're aware, but you're using Python2, not Python3. This means that input() acts as basically a calculator, typing in 3 + 1 into input() will return 4, whereas typing in 3 + 1 into raw_input() will return 3 + 1, which is what I assume you want :)

To fix this: Replace all instances of input with raw_input, and you should be good to go!
Alternatively you could switch to Python3 :)