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;
        char[][] field = new char[h][];
        UnionFindTree uft = new UnionFindTree(h * w);
        for (int i = 0; i < h; i++) {
            field[i] = sc.next().toCharArray();
            for (int j = 1; j < w; j++) {
                if (Math.abs(field[i][j - 1] - field[i][j]) <= 1) {
                    uft.unite(i * w + j - 1, i * w + j);
                }
            }
            for (int j = 2; j < w; j++) {
                if (field[i][j - 2] == field[i][j] && field[i][j - 1] < field[i][j]) {
                    uft.unite(i * w + j - 2, i * w + j);
                }
            }
            if (i <= 0) {
                continue;
            }
            for (int j = 0; j < w; j++) {
                if (Math.abs(field[i - 1][j] - field[i][j]) <= 1) {
                    uft.unite((i - 1) * w + j, i * w + j);
                }
            }
            if (i <= 1) {
                continue;
            }
            for (int j = 0; j < w; j++) {
                if (field[i - 2][j] == field[i][j] && field[i - 1][j] < field[i][j]) {
                    uft.unite((i - 2) * w + j, i * w + j);
                }
            }
        }
        if (uft.same(start, goal)) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
    
    static class UnionFindTree {
        int[] parents;
        
        public UnionFindTree(int size) {
            parents = new int[size];
            for (int i = 0; i < size; i++) {
                parents[i] = i;
            }
        }
        
        public int find(int x) {
            if (x == parents[x]) {
                return x;
            } else {
                return parents[x] = find(parents[x]);
            }
        }
        
        public boolean same(int x, int y) {
            return find(x) == find(y);
        }
        
        public void unite(int x, int y) {
            if (!same(x, y)) {
                parents[find(x)] = find(y);
            }
        }
    }
}
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 {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}