title: Find the time period with the maximum number of overlapping intervals
body: <p>There is one very famous problem. I am asking the same here.<br>
  There is number of elephants time span given, here time span means, year of birth to year of death.<br>
  You have to calculate the period where maximum number of elephants are alive.</p>
  
  <p><strong>Example:</strong></p>
  
  <pre><code>1990 - 2013
  1995 - 2000
  2010 - 2020
  1992 - 1999
  
  Answer is   1995 - 1999
  </code></pre>
  
  <p>I tried hard to solve this, but I am unable to do so.</p>
  
  <p>How can I solve this problem?</p>
  
  <p>I got approach for when a user asks to find the number of elephants in any year. I solved that by using segment tree, whenever any elephants time span given, increase every year of that time span by 1. We can solve that in this way. Can this be used to solve the above problem?</p>
  
  <p><strong>For above question, I only need the high-level approach, I will code it myself.</strong> </p>