<p>Given a string <code>n</code> representing an integer, return <em>the closest integer (not including itself), which is a palindrome</em>. If there is a tie, return <em><strong>the smaller one</strong></em>.</p> <p>The closest is defined as the absolute difference minimized between two integers.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> n = "123" <strong>Output:</strong> "121" </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> n = "1" <strong>Output:</strong> "0" <strong>Explanation:</strong> 0 and 2 are the closest palindromes but we return the smallest which is 0. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n.length <= 18</code></li> <li><code>n</code> consists of only digits.</li> <li><code>n</code> does not have leading zeros.</li> <li><code>n</code> is representing an integer in the range <code>[1, 10<sup>18</sup> - 1]</code>.</li> </ul>