import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int h = sc.nextInt();
        int w = sc.nextInt();
        int start = (sc.nextInt() - 1) * w + sc.nextInt() - 1;
        int goal =  (sc.nextInt() - 1) * w + sc.nextInt() - 1;
        ArrayList<ArrayList<Integer>> graph = new ArrayList<>();
        char[][] field = new char[h][];
        for (int i = 0; i < h; i++) {
            field[i] = sc.next().toCharArray();
            for (int j = 0; j < w; j++) {
                graph.add(new ArrayList<>());
                if (i > 0 && Math.abs(field[i][j] - field[i - 1][j]) <= 1) {
                    graph.get(i * w + j).add((i - 1) * w + j);
                    graph.get((i - 1) * w + j).add(i * w + j);
                }
                if (i > 1 && field[i][j] == field[i - 2][j] && field[i][j] > field[i - 1][j]) {
                    graph.get(i * w + j).add((i - 2) * w + j);
                    graph.get((i - 2) * w + j).add(i * w + j);
                }
                if (j > 0 && Math.abs(field[i][j] - field[i][j - 1]) <= 1) {
                    graph.get(i * w + j).add(i * w + j - 1);
                    graph.get(i * w + j - 1).add(i * w + j);
                }
                if (j > 1 && field[i][j] == field[i][j - 2] && field[i][j] > field[i][j - 1]) {
                    graph.get(i * w + j).add(i * w + j - 2);
                    graph.get(i * w + j - 2).add(i * w + j);
                }
            }
        }
        ArrayDeque<Integer> deq = new ArrayDeque<>();
        deq.add(start);
        boolean[] visited = new boolean[h * w];
        while (deq.size() > 0) {
            int x = deq.poll();
            if (visited[x]) {
                continue;
            }
            visited[x] = true;
            deq.addAll(graph.get(x));
        }
        if (visited[goal]) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}

class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}