#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

const int dy[] = {-1, 1, 0, 0};
const int dx[] = {0, 0, -1, 1};

int main()
{
    int h, w, sy, sx, gy, gx;
    cin >> h >> w >> sy >> sx >> gy >> gx;
    -- sy;
    -- sx;
    -- gy;
    -- gx;

    vector<string> s(h);
    for(int i=0; i<h; ++i)
        cin >> s[i];

    queue<pair<int, int> > q;
    vector<vector<bool> > check(h, vector<bool>(w, false));
    q.push(make_pair(sy, sx));
    check[sy][sx] = true;
    while(!q.empty()){
        int y = q.front().first;
        int x = q.front().second;
        q.pop();
        if(y == gy && x == gx){
            cout << "YES" << endl;
            return 0;
        }

        for(int i=0; i<4; ++i){
            int y2 = y + dy[i];
            int x2 = x + dx[i];
            if(!(0 <= y2 && y2 < h && 0 <= x2 && x2 < w))
                continue;

            if(!check[y2][x2] && abs(s[y2][x2] - s[y][x]) <= 1){
                q.push(make_pair(y2, x2));
                check[y2][x2] = true;
            }

            if(s[y2][x2] < s[y][x]){
                y2 += dy[i];
                x2 += dx[i];
                if(!(0 <= y2 && y2 < h && 0 <= x2 && x2 < w))
                    continue;

                if(!check[y2][x2] && s[y2][x2] == s[y][x]){
                    q.push(make_pair(y2, x2));
                    check[y2][x2] = true;
                }
            }
        }
    }

    cout << "NO" << endl;
    return 0;
}