<p>You are given two strings <code>s</code> and <code>p</code> where <code>p</code> is a <strong>subsequence </strong>of <code>s</code>. You are also given a <strong>distinct 0-indexed </strong>integer array <code>removable</code> containing a subset of indices of <code>s</code> (<code>s</code> is also <strong>0-indexed</strong>).</p>
<p>You want to choose an integer <code>k</code> (<code>0 <= k <= removable.length</code>) such that, after removing <code>k</code> characters from <code>s</code> using the <strong>first</strong><code>k</code> indices in <code>removable</code>, <code>p</code> is still a <strong>subsequence</strong> of <code>s</code>. More formally, you will mark the character at <code>s[removable[i]]</code> for each <code>0 <= i < k</code>, then remove all marked characters and check if <code>p</code> is still a subsequence.</p>
<p>Return <em>the <strong>maximum</strong></em><code>k</code><em> you can choose such that </em><code>p</code><em> is still a <strong>subsequence</strong> of </em><code>s</code><em> after the removals</em>.</p>
<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>
<strong>Input:</strong> s = "abcacb", p = "ab", removable = [3,1,0]
<strong>Output:</strong> 2
<strong>Explanation</strong>: After removing the characters at indices 3 and 1, "a<s><strong>b</strong></s>c<s><strong>a</strong></s>cb" becomes "accb".
"ab" is a subsequence of "<strong><u>a</u></strong>cc<strong><u>b</u></strong>".
If we remove the characters at indices 3, 1, and 0, "<s><strong>ab</strong></s>c<s><strong>a</strong></s>cb" becomes "ccb", and "ab" is no longer a subsequence.
