import java.io.PrintStream;
import java.util.Scanner;


public class Y424 {
	int h, w, sx, sy, tx, ty;
	String[] s;
	boolean[][] visited;
	
	static int[] dx = { 0, 1, 0, -1 };
	static int[] dy = { 1, 0, -1, 0 };
	
	Y424() throws Exception {
		Scanner in = new Scanner(System.in);
		PrintStream out = new PrintStream(System.out);
		
		h = in.nextInt();
		w = in.nextInt();
		sx = in.nextInt();
		sy = in.nextInt();
		tx = in.nextInt();
		ty = in.nextInt();
		s = new String[h];
		for (int i = 0; i < h; i++) {
			s[i] = in.next();
		}
		
		visited = new boolean[h][w];
		
		visited[sx-1][sy-1] = true;
		dfs(sx-1, sy-1);
		
		if (visited[tx-1][ty-1]) {
			out.println("YES");
		} else {
			out.println("NO");
		}
		
		out.flush();
	}
	
	void dfs(int x, int y) {
		for (int dir = 0; dir < 4; dir++) {
			int xx = x + dx[dir];
			int yy = y + dy[dir];
			
			if (0 <= xx && xx < h && 0 <= yy && yy < w) {
				if (Math.abs((int)s[xx].charAt(yy) - (int)s[x].charAt(y)) <= 1 && !visited[xx][yy]) {
					visited[xx][yy] = true;
					dfs(xx, yy);
				}
							
				int xxx = x + 2 * dx[dir];
				int yyy = y + 2 * dy[dir];
			
				if (0 <= xxx && xxx < h && 0 <= yyy && yyy < w) {
					if (s[x].charAt(y) == s[xxx].charAt(yyy) && (int)s[x].charAt(y) > (int)s[xx].charAt(yy)) {
						if (!visited[xxx][yyy]) {
							visited[xxx][yyy] = true;
							dfs(xxx, yyy);
						}
					}
				}
			}		
		}
	}

	public static void main(String argv[]) throws Exception {
		new Y424();
	}
}