15. Extract Even Bits Only from 32-bit Register

From a 32-bit register, extract all even-positioned bits (0, 2, 4, …, 30).
Return the compressed value formed by only these bits (shifted to be consecutive).

Example 1

Input: reg = 0b0101 0101 
Output: 0b1111

Example 2 

Input: reg = 0b1010 1010 
Output: 0b0000