title: how to find the minimum value of z in the range l to r such that (x & z).(y & z) is maximum
body: <p>For e.g:- if x=11,y=21,l=16 and r=21,then the minimum value of z satisfying the question's condition in the range l to r is 19 i.e (11 &amp; 19).(21 &amp; 19) is maximum </p>
  
  <p>i can't figure out how to solve this question for large range</p>