import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		//FastScanner scanner=new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		int h=scanner.nextInt();
		int w=scanner.nextInt();
		int sx=scanner.nextInt();
		int sy=scanner.nextInt();
		int gx=scanner.nextInt();
		int gy=scanner.nextInt();
		sx--; sy--; gx--; gy--;
		char[][] b=new char[h][w];
		for(int i=0; i<h; i++) {
			b[i]=scanner.next().toCharArray();
		}
		int[] dx= {1, -1, 0, 0};
		int[] dy= {0, 0, 1, -1};
		Queue<Integer> que=new ArrayDeque<Integer>();
		que.offer(sx*w+sy);
		boolean[][] used=new boolean[h][w];
		used[sx][sy]=true;
		while(que.size()>0) {
			int xy=que.poll();
			int x=xy/w, y=xy%w;
			for(int k=0; k<4; k++) {
				int x1=x+dx[k], y1=y+dy[k];
				if(x1<0 || x1>=h || y1<0 || y1>=w) continue;
				if(!used[x1][y1] && Math.abs((int)(b[x][y]-b[x1][y1]))<=1) {
					used[x1][y1]=true;
					que.offer(x1*w+y1);
				}
				int x2=x+2*dx[k], y2=y+2*dy[k];
				if(x2<0 || x2>=h || y2<0 || y2>=w) continue;
				if(!used[x2][y2] && b[x][y]==b[x2][y2] && b[x][y]>=b[x1][y1]) {
					used[x2][y2]=true;
					que.offer(x2*w+y2);
				}
			}
		}
		if(used[gx][gy]) out.println("YES");
		else out.println("NO");
		out.close();
		scanner.close();
	}
}

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 static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		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() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}