<p>An integer <code>x</code> is a <strong>good</strong> if after rotating each digit individually by 180 degrees, we get a valid number that is different from <code>x</code>. Each digit must be rotated - we cannot choose to leave it alone.</p> <p>A number is valid if each digit remains a digit after rotation. For example:</p> <ul> <li><code>0</code>, <code>1</code>, and <code>8</code> rotate to themselves,</li> <li><code>2</code> and <code>5</code> rotate to each other (in this case they are rotated in a different direction, in other words, <code>2</code> or <code>5</code> gets mirrored),</li> <li><code>6</code> and <code>9</code> rotate to each other, and</li> <li>the rest of the numbers do not rotate to any other number and become invalid.</li> </ul> <p>Given an integer <code>n</code>, return <em>the number of <strong>good</strong> integers in the range </em><code>[1, n]</code>.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> n = 10 <strong>Output:</strong> 4 <strong>Explanation:</strong> There are four good numbers in the range [1, 10] : 2, 5, 6, 9. Note that 1 and 10 are not good numbers, since they remain unchanged after rotating. </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> n = 1 <strong>Output:</strong> 0 </pre> <p><strong class="example">Example 3:</strong></p> <pre> <strong>Input:</strong> n = 2 <strong>Output:</strong> 1 </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n <= 10<sup>4</sup></code></li> </ul>