Find the value of $2^{-(2k+1)} - 2^{-(2k-1)} + 2^{-2k}$. The original answer is in the form $-x*2^{-(y*z+k)}$, where x, y, and z are integers. Please provide the sum of x, y, and z.

Let's think step by step and output the final answer within \boxed{}.
user