Algorithms: Step by Step please.

Kindly, no handwriting please, and thanks a lot:

Problem 2. a) What does the following algorithm do? Analyze its worst-case running time, and express it using "Big-Oh" notation. Algorithm Foo (a, n): Input: two integers, a and Output:? k0 b=1 while k 0 do if k mod 2 = 0 then kk/2 else kk-1 return b