title: Count the data in the nested list python
body: <p>I have a nested list. In the list, it has a date and a name. I want the count the users on the date. For example,In '2019-10-11', there are 5 users. But sam user already exists, so i count it as 4. Here's the list</p>
  
  <pre><code>a =[['sam', '2019-10-11'], ['ram', '2019-10-12'], ['king', '2019-10-11'],
      ['queen', '2019-10-10'], ['ram', '2019-10-12'], ['kumar', '2019-10-11'],
      ['jeba', '2019-10-11'], ['sam', '2019-10-10'], ['sam', '2019-10-11'],
      ['howl', '2019-10-14']]
  </code></pre>
  
  <p>Output Required:</p>
  
  <pre><code>a = [['2019-10-10','2019-10-11','2019-10-12','2019-10-14'],[2,4,1,1]]
  </code></pre>