import java.util.*;

public class Main {
    static int h;
    static int w;
    static char[][] field;
    static boolean[][] visited;
    
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		h = sc.nextInt();
		w = sc.nextInt();
		int sh = sc.nextInt() - 1;
		int sw = sc.nextInt() - 1;
		int gh = sc.nextInt() - 1;
		int gw = sc.nextInt() - 1;
		field = new char[h][];
		visited = new boolean[h][w];
		for (int i = 0; i < h; i++) {
		    field[i] = sc.next().toCharArray();
		}
		visit(sh, sw);
		if (visited[gh][gw]) {
		    System.out.println("YES");
		} else {
		    System.out.println("NO");
		}
	}
	
	static void visit(int hh, int ww) {
	    if (visited[hh][ww]) {
	        return;
	    }
	    visited[hh][ww] = true;
	    if (hh > 0 && Math.abs(field[hh][ww] - field[hh - 1][ww]) <= 1) {
	        visit(hh - 1, ww);
	    }
	    if (hh < h - 1 && Math.abs(field[hh][ww] - field[hh + 1][ww]) <= 1) {
	        visit(hh + 1, ww);
	    }
	    if (ww > 0 && Math.abs(field[hh][ww] - field[hh][ww - 1]) <= 1) {
	        visit(hh, ww - 1);
	    }
	    if (ww < w - 1 && Math.abs(field[hh][ww] - field[hh][ww + 1]) <= 1) {
	        visit(hh, ww + 1);
	    }
	    if (hh > 1 && field[hh][ww] == field[hh - 2][ww] && field[hh][ww] > field[hh - 1][ww]) {
	        visit(hh - 2, ww);
	    }
	    if (hh < h - 2 && field[hh][ww] == field[hh + 2][ww] && field[hh][ww] > field[hh + 1][ww]) {
	        visit(hh + 2, ww);
	    }
	    if (ww > 1 && field[hh][ww] == field[hh][ww - 2] && field[hh][ww] > field[hh][ww - 1]) {
	        visit(hh, ww - 2);
	    }
	    if (ww < w - 2 && field[hh][ww] == field[hh][ww + 2] && field[hh][ww] > field[hh][ww + 1]) {
	        visit(hh, ww + 2);
	    }
	}
}