<p>You're given strings <code>jewels</code> representing the types of stones that are jewels, and <code>stones</code> representing the stones you have. Each character in <code>stones</code> is a type of stone you have. You want to know how many of the stones you have are also jewels.</p> <p>Letters are case sensitive, so <code>"a"</code> is considered a different type of stone from <code>"A"</code>.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre><strong>Input:</strong> jewels = "aA", stones = "aAAbbbb" <strong>Output:</strong> 3 </pre><p><strong>Example 2:</strong></p> <pre><strong>Input:</strong> jewels = "z", stones = "ZZ" <strong>Output:</strong> 0 </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= jewels.length, stones.length <= 50</code></li> <li><code>jewels</code> and <code>stones</code> consist of only English letters.</li> <li>All the characters of <code>jewels</code> are <strong>unique</strong>.</li> </ul>