Untitled

import java.util.Scanner;

public class StoneGame {

    private static final char WHITE = 'w';
    private static final char BLACK = 'b';

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int testCaseCount = scanner.nextInt();
        for (int testCaseNumber = 1; testCaseNumber <= testCaseCount; testCaseNumber++) {
            char[][] board = new char[4][4];
            for (int row = 0; row < 4; row++) {
                String line = scanner.next();
                for (int col = 0; col < 4; col++) {
                    board[row][col] = line.charAt(col);
                }
            }

            int minimumOperationCount = Integer.MAX_VALUE;

            backtrack(board, 0, 0, 0, 0, minimumOperationCount);

            if (minimumOperationCount == Integer.MAX_VALUE) {
                System.out.println("Case #" + testCaseNumber + " impossible");
            } else {
                System.out.println("Case #" + testCaseNumber + " " + minimumOperationCount);
            }
        }
        scanner.close();
    }

    private static void backtrack(char[][] board, int row, int col, int whiteCount, int blackCount, int minimumOperationCount) {
        if (row == 4) {
            if (whiteCount == 0 || blackCount == 0) {
                minimumOperationCount = Math.min(minimumOperationCount, Math.max(whiteCount, blackCount));
            }
            return;
        }

        if (minimumOperationCount <= Math.max(whiteCount, blackCount)) {
            return;
        }

        for (int rowOffset = -1; rowOffset <= 1; rowOffset++) {
            for (int colOffset = -1; colOffset <= 1; colOffset++) {
                if (rowOffset == 0 && colOffset == 0) {
                    continue;
                }

                int newRow = row + rowOffset;
                int newCol = col + colOffset;

                if (isValidCell(board, newRow, newCol)) {
                    board[row][col] = board[newRow][newCol] == WHITE ? BLACK : WHITE;
                    backtrack(board, newRow, newCol, whiteCount + (board[row][col] == WHITE ? 1 : -1), blackCount + (board[row][col] == BLACK ? 1 : -1), minimumOperationCount);
                    board[row][col] = board[newRow][newCol] == WHITE ? BLACK : WHITE; // Restore original value
                }
            }
        }
    }

    private static boolean isValidCell(char[][] board, int row, int col) {
        return 0 <= row && row < 4 && 0 <= col && col < 4;
    }
}