<p>You are given an <code>n x n</code> binary grid <code>board</code>. In each move, you can swap any two rows with each other, or any two columns with each other.</p> <p>Return <em>the minimum number of moves to transform the board into a <strong>chessboard board</strong></em>. If the task is impossible, return <code>-1</code>.</p> <p>A <strong>chessboard board</strong> is a board where no <code>0</code>'s and no <code>1</code>'s are 4-directionally adjacent.</p> <p> </p> <p><strong>Example 1:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard1-grid.jpg" style="width: 500px; height: 145px;" /> <pre> <strong>Input:</strong> board = [[0,1,1,0],[0,1,1,0],[1,0,0,1],[1,0,0,1]] <strong>Output:</strong> 2 <strong>Explanation:</strong> One potential sequence of moves is shown. The first move swaps the first and second column. The second move swaps the second and third row. </pre> <p><strong>Example 2:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard2-grid.jpg" style="width: 164px; height: 165px;" /> <pre> <strong>Input:</strong> board = [[0,1],[1,0]] <strong>Output:</strong> 0 <strong>Explanation:</strong> Also note that the board with 0 in the top left corner, is also a valid chessboard. </pre> <p><strong>Example 3:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2021/06/29/chessboard3-grid.jpg" style="width: 164px; height: 165px;" /> <pre> <strong>Input:</strong> board = [[1,0],[1,0]] <strong>Output:</strong> -1 <strong>Explanation:</strong> No matter what sequence of moves you make, you cannot end with a valid chessboard. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>n == board.length</code></li> <li><code>n == board[i].length</code></li> <li><code>2 <= n <= 30</code></li> <li><code>board[i][j]</code> is either <code>0</code> or <code>1</code>.</li> </ul>