title: Checking even or odd `1` bits in a number
body: <p>I want to check if number has all even or odd bits set to one and only them. For eg.:</p>
  
  <p>Number <code>42</code> is correct, because in a binary code <code>101010</code> it has all and only even bits sets to <code>1</code>.
  Number <code>21</code> is also correct, <code>10101</code>.</p>
  
  <p>Number <code>69</code> for eg. <code>1000101</code> is not correct, because there are only three odd bits sets to <code>1</code>.</p>
  
  <p>I've tried using different operations with <code>^, &amp;, &gt;&gt;, &lt;&lt;</code> and i still have no idea how can i do this using these operators. Yes, i need to do this using logical operators in <code>C</code>.</p>