<p>Given two integers <code>a</code> and <code>b</code>, return <strong>any</strong> string <code>s</code> such that:</p> <ul> <li><code>s</code> has length <code>a + b</code> and contains exactly <code>a</code> <code>'a'</code> letters, and exactly <code>b</code> <code>'b'</code> letters,</li> <li>The substring <code>'aaa'</code> does not occur in <code>s</code>, and</li> <li>The substring <code>'bbb'</code> does not occur in <code>s</code>.</li> </ul> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> a = 1, b = 2 <strong>Output:</strong> "abb" <strong>Explanation:</strong> "abb", "bab" and "bba" are all correct answers. </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> a = 4, b = 1 <strong>Output:</strong> "aabaa" </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>0 <= a, b <= 100</code></li> <li>It is guaranteed such an <code>s</code> exists for the given <code>a</code> and <code>b</code>.</li> </ul>