<p>You are given a very large integer <code>n</code>, represented as a string, and an integer digit <code>x</code>. The digits in <code>n</code> and the digit <code>x</code> are in the <strong>inclusive</strong> range <code>[1, 9]</code>, and <code>n</code> may represent a <b>negative</b> number.</p> <p>You want to <strong>maximize </strong><code>n</code><strong>'s numerical value</strong> by inserting <code>x</code> anywhere in the decimal representation of <code>n</code>. You <strong>cannot</strong> insert <code>x</code> to the left of the negative sign.</p> <ul> <li>For example, if <code>n = 73</code> and <code>x = 6</code>, it would be best to insert it between <code>7</code> and <code>3</code>, making <code>n = 763</code>.</li> <li>If <code>n = -55</code> and <code>x = 2</code>, it would be best to insert it before the first <code>5</code>, making <code>n = -255</code>.</li> </ul> <p>Return <em>a string representing the <strong>maximum</strong> value of </em><code>n</code><em> after the insertion</em>.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> n = "99", x = 9 <strong>Output:</strong> "999" <strong>Explanation:</strong> The result is the same regardless of where you insert 9. </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> n = "-13", x = 2 <strong>Output:</strong> "-123" <strong>Explanation:</strong> You can make n one of {-213, -123, -132}, and the largest of those three is -123. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n.length <= 10<sup>5</sup></code></li> <li><code>1 <= x <= 9</code></li> <li>The digits in <code>n</code> are in the range <code>[1, 9]</code>.</li> <li><code>n</code> is a valid representation of an integer.</li> <li>In the case of a negative <code>n</code>, it will begin with <code>'-'</code>.</li> </ul>