#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int H,W;
vector<string> V;
vector< vector<int> > D;

struct Point {
    Point(){};
    Point( int a, int b ){ x = a; y = b; };
    int x;
    int y;
};

Point S, G;

int dir[4][2] = { {1,0}, {0,1}, {-1,0}, {0,-1} };

bool isOK( int x, int y ) {
    return x >= 0 && y >= 0 && x < W && y < H;
}

bool func( Point p ) {
    // cout << p.x << " " << p.y << endl;

    if ( p.x == G.x && p.y == G.y ) { return true; }

    D[p.y][p.x] = 1;

    Point np;
    for ( int i = 0; i < 4; i++ ) {
        int nx1 = p.x + dir[i][0];
        int ny1 = p.y + dir[i][1];
        np.x = nx1;
        np.y = ny1;
        if (isOK(nx1,ny1) && D[ny1][nx1] == 0 && ( abs( V[p.y][p.x]-V[ny1][nx1] ) <= 1 ) && func( np ) ) {
            return true;
        }
        int nx2 = p.x + dir[i][0]*2;
        int ny2 = p.y + dir[i][1]*2;
        np.x = nx2;
        np.y = ny2;
        if ( isOK(nx2,ny2) && D[ny2][nx2] == 0 && V[p.y][p.x] == V[ny2][nx2] && V[p.y][p.x] > V[ny1][nx1] && func( np ) ) {
            return true;
        }
    }
    return false;
}

int main() {
    
    cin >> H >> W;
    int sx,sy,gx,gy;
    cin >> sy >> sx >> gy >> gx;
    sx--; sy--; gx--; gy--;
    S.x = sx; S.y = sy;
    G.x = gx; G.y = gy;
    
    V.resize(H);
    D.resize(H);    
    for ( int i = 0; i < H; i++ ) {
        cin >> V[i];
        D[i].resize(W,0);
    }

    cout << ( func( S ) ? "YES" : "NO" ) << endl;


    return 0;
}