Hi, your solution looks almost like my one, but you can improve it by leaving "len(string)" out of your slicing in the "POP" case. It will work the same way ;) More

Hi, nice code :) A small improvement suggestion: if "PUSH" in i: queue += i[-1] elif len(queue): queue = queue[1:] This will make your code shorter and more readable ;) More

You can solve this in one line as well: return bin(number)[2:].count('1') :) More