import java.io.*;
import java.util.*;
public class Main {
	static long MOD = 2 << 29;
	public static void main(String[] args) {
		FastScanner sc = new FastScanner();
		int H = sc.nextInt();
		int W = sc.nextInt();
		int sy = sc.nextInt()-1;
		int sx = sc.nextInt()-1;
		int gy = sc.nextInt()-1;
		int gx = sc.nextInt()-1;
		char[][] map = new char[H][];
		for(int i = 0; i < H; i++) {
			map[i] = sc.next().toCharArray();
		}
		boolean[][] cap = new boolean[H][W];
		int[] vx = {0,1,0,-1};
		int[] vy = {1,0,-1,0};
		ArrayDeque<Data> q = new ArrayDeque<Data>();
		q.add(new Data(sx,sy));
		while(!q.isEmpty()) {
			Data p = q.poll();
			if(cap[p.y][p.x]) continue;
			cap[p.y][p.x] = true;
			for(int i = 0; i < 4; i++) {
				int tx = vx[i] + p.x;
				int ty = vy[i] + p.y;
				if(!rcheck(tx,ty,W,H)) continue;
				if(Math.abs(map[ty][tx] - map[p.y][p.x]) > 1) continue;
				if(cap[ty][tx]) continue;
				q.add(new Data(tx,ty));
			}
			for(int i = 0; i < 4; i++) {
				int tx = vx[i]*2 + p.x;
				int ty = vy[i]*2 + p.y;
				int tx2 = vx[i] + p.x;
				int ty2 = vy[i] + p.y;
				if(!rcheck(tx,ty,W,H)) continue;
				if(Math.abs(map[ty][tx] - map[p.y][p.x]) != 0 || map[ty2][tx2] >= map[p.y][p.x]) continue;
				if(cap[ty][tx]) continue;
				q.add(new Data(tx,ty));
			}	
		}
		if(cap[gy][gx]) System.out.println("YES");
		else System.out.println("NO");
		
	}
	static boolean rcheck(int x, int y, int W, int H) {
		if(x < 0 || y < 0 || x >= W || y >= H) return false;
		return true;
	}
	static class Data {
		int x;
		int y;
		Data(int a, int b) {
			x = a;
			y = b;
		}
	}
	
	
	
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
    public boolean hasNext() { skipUnprintable(); return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        if (!hasNext()) throw new NoSuchElementException();
        int n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
}