title: Appropriate data structure for storing the data
body: <p>I should store the following data, where the first integer is unique:</p>
  
  <pre><code>&lt;118,15&gt;
  &lt;429,15&gt;
  &lt;625,30&gt;
  </code></pre>
  
  <p>Is <code>HashSet&lt;Integer,Integer&gt;</code> the good option to store this?</p>