// Project FloodFill2

// Search maze from start point (xStart, yStart) to
// end point (xEnd, yEnd).  Here is the search order
// from the current point *:
//            4
//          3 * 2
//            1

import java.io.PrintWriter;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class FloodFill2
{
    public static int height, width, xStart, yStart;
    private static char[ ][ ] array;

    public static void main(String[ ] args)
                       throws FileNotFoundException
    {
        initialize( );
        fill(xStart, yStart);
        printResult( );
    }

    public static void initialize()
                       throws FileNotFoundException
    {
        Scanner s = new Scanner(new FileReader("region.txt"));
        String line = "";

        // Read maze from file.
        height = s.nextInt( );
        width = s.nextInt( );
        xStart = s.nextInt( );
        yStart = s.nextInt( );

        // Remove end of numeric input line.
        line = s.nextLine( );

        // Instantiate and populate array.
        array = new char[height][width];
        for(int y = 0; y <= height - 1; y++)
        {
            line = s.nextLine( );
            for(int x = 0; x <= width - 1; x++)
                array[y][x] = line.charAt(x);
        }
    }

    // Recursive FloodFill routine.
    public static void fill(int x, int y)
    {
        if (array[y][x] == ' ')
        {
            array[y][x] = '@';
            fill(x, y + 1);
            fill(x + 1, y);
            fill(x - 1, y);
            fill(x, y - 1);
        }
    }

    public static void printResult( )
                       throws FileNotFoundException
    {
        PrintWriter fw = new PrintWriter("filledregion.txt");

        // Print result.
        for(int y = 0; y <= width - 1; y++)
        {
            for(int x = 0; x <= height - 1; x++)
                fw.print(array[y][x]);
            fw.println( );
        }
        fw.close( );
    }
}