<p>You are given a positive integer array <code>skill</code> of <strong>even</strong> length <code>n</code> where <code>skill[i]</code> denotes the skill of the <code>i<sup>th</sup></code> player. Divide the players into <code>n / 2</code> teams of size <code>2</code> such that the total skill of each team is <strong>equal</strong>.</p> <p>The <strong>chemistry</strong> of a team is equal to the <strong>product</strong> of the skills of the players on that team.</p> <p>Return <em>the sum of the <strong>chemistry</strong> of all the teams, or return </em><code>-1</code><em> if there is no way to divide the players into teams such that the total skill of each team is equal.</em></p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> skill = [3,2,5,1,3,4] <strong>Output:</strong> 22 <strong>Explanation:</strong> Divide the players into the following teams: (1, 5), (2, 4), (3, 3), where each team has a total skill of 6. The sum of the chemistry of all the teams is: 1 * 5 + 2 * 4 + 3 * 3 = 5 + 8 + 9 = 22. </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> skill = [3,4] <strong>Output:</strong> 12 <strong>Explanation:</strong> The two players form a team with a total skill of 7. The chemistry of the team is 3 * 4 = 12. </pre> <p><strong class="example">Example 3:</strong></p> <pre> <strong>Input:</strong> skill = [1,1,2,3] <strong>Output:</strong> -1 <strong>Explanation:</strong> There is no way to divide the players into teams such that the total skill of each team is equal. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>2 <= skill.length <= 10<sup>5</sup></code></li> <li><code>skill.length</code> is even.</li> <li><code>1 <= skill[i] <= 1000</code></li> </ul>