How to get first index of Binary Search's results?
<p>I have some problems. I have 2 list such as:</p>

<pre><code>List&lt;int&gt; firstList = new List&lt;int&gt; { 1, 2, 2, 3, 5};

List&lt;int&gt; secondList = new List&lt;int&gt; { 2, 3, 1 };
</code></pre>

<p>⇒ True result is: <code>{1, 3, 0}</code></p>

<p>I would like to get the first index of numbers in secondList that exists in firstList. I used <code>list.BinarySearch()</code> but the result was <code>{2, 3, 0}</code>.</p>