<p>Given a string <code>s</code> of lower and upper case English letters.</p> <p>A good string is a string which doesn't have <strong>two adjacent characters</strong> <code>s[i]</code> and <code>s[i + 1]</code> where:</p> <ul> <li><code>0 <= i <= s.length - 2</code></li> <li><code>s[i]</code> is a lower-case letter and <code>s[i + 1]</code> is the same letter but in upper-case or <strong>vice-versa</strong>.</li> </ul> <p>To make the string good, you can choose <strong>two adjacent</strong> characters that make the string bad and remove them. You can keep doing this until the string becomes good.</p> <p>Return <em>the string</em> after making it good. The answer is guaranteed to be unique under the given constraints.</p> <p><strong>Notice</strong> that an empty string is also good.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> s = "leEeetcode" <strong>Output:</strong> "leetcode" <strong>Explanation:</strong> In the first step, either you choose i = 1 or i = 2, both will result "leEeetcode" to be reduced to "leetcode". </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> s = "abBAcC" <strong>Output:</strong> "" <strong>Explanation:</strong> We have many possible scenarios, and all lead to the same answer. For example: "abBAcC" --> "aAcC" --> "cC" --> "" "abBAcC" --> "abBA" --> "aA" --> "" </pre> <p><strong class="example">Example 3:</strong></p> <pre> <strong>Input:</strong> s = "s" <strong>Output:</strong> "s" </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= s.length <= 100</code></li> <li><code>s</code> contains only lower and upper case English letters.</li> </ul>