<p>We define the usage of capitals in a word to be right when one of the following cases holds:</p> <ul> <li>All letters in this word are capitals, like <code>"USA"</code>.</li> <li>All letters in this word are not capitals, like <code>"leetcode"</code>.</li> <li>Only the first letter in this word is capital, like <code>"Google"</code>.</li> </ul> <p>Given a string <code>word</code>, return <code>true</code> if the usage of capitals in it is right.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre><strong>Input:</strong> word = "USA" <strong>Output:</strong> true </pre><p><strong>Example 2:</strong></p> <pre><strong>Input:</strong> word = "FlaG" <strong>Output:</strong> false </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= word.length <= 100</code></li> <li><code>word</code> consists of lowercase and uppercase English letters.</li> </ul>