title: B-Trees insertion
body: <p>How do I add 35?</p>
  
  <p>How do I know whether to move a key up(up to the node with 34 and 78, and if I do that, which key do I move up) and make more children(to fulfill the "A non-leaf node with k children contains k−1 keys." rule)</p>
  
  <p>OR</p>
  
  <p>just split up the 39,44,56,74(and 35) node into three children, like what I did in step 8.</p>
  
  <p><img src="https://i.stack.imgur.com/FkLUG.png" alt="http://i.imgur.com/cwJOdMd.png"></p>