<p>The <strong>product difference</strong> between two pairs <code>(a, b)</code> and <code>(c, d)</code> is defined as <code>(a * b) - (c * d)</code>.</p>
<ul>
<li>For example, the product difference between <code>(5, 6)</code> and <code>(2, 7)</code> is <code>(5 * 6) - (2 * 7) = 16</code>.</li>
</ul>
<p>Given an integer array <code>nums</code>, choose four <strong>distinct</strong> indices <code>w</code>, <code>x</code>, <code>y</code>, and <code>z</code> such that the <strong>product difference</strong> between pairs <code>(nums[w], nums[x])</code> and <code>(nums[y], nums[z])</code> is <strong>maximized</strong>.</p>
<p>Return <em>the <strong>maximum</strong> such product difference</em>.</p>
<p> </p>
<p><strong>Example 1:</strong></p>
<pre>
<strong>Input:</strong> nums = [5,6,2,7,4]
<strong>Output:</strong> 34
<strong>Explanation:</strong> We can choose indices 1 and 3 for the first pair (6, 7) and indices 2 and 4 for the second pair (2, 4).
The product difference is (6 * 7) - (2 * 4) = 34.
</pre>
<p><strong>Example 2:</strong></p>
<pre>
<strong>Input:</strong> nums = [4,2,5,9,7,4,8]
<strong>Output:</strong> 64
<strong>Explanation:</strong> We can choose indices 3 and 6 for the first pair (9, 8) and indices 1 and 5 for the second pair (2, 4).
