#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
using pll = pair<ll,ll>;
constexpr int INF = 1e9;
constexpr ll LINF = 1e18;
constexpr int MOD = 1000000007;
vector<int> dx = {0,0,1,-1,0,0,2,-2};
vector<int> dy = {1,-1,0,0,2,-2,0,0};

int main(){
    int h,w;
    cin >> h >> w;
    int sx,sy,gx,gy;
    cin >> sx >> sy >> gx >> gy;
    --sx;--sy;--gx;--gy;
    vector<string> maze(h);
    rep(i,h) cin >> maze[i];
    vector<vector<bool>> seen(h,vector<bool>(w,false));
    queue<P> q;
    q.push(P(sx,sy));
    while(!q.empty()){
        int x,y;
        tie(x,y) = q.front();
        q.pop();
        if(seen[x][y]) continue;
        seen[x][y] = true;
        rep(i,4){
            int new_x = x + dx[i];
            int new_y = y + dy[i];
            if(0 <= new_x && new_x < h && 0 <= new_y && new_y < w){
                if(abs(maze[x][y]-maze[new_x][new_y]) <= 1 && !seen[new_x][new_y]){
                    q.push(P(new_x,new_y));
                }
            }
        }
        for(int i=4;i<8;i++){
            int new_x = x + dx[i];
            int new_y = y + dy[i];
            if(0 <= new_x && new_x < h && 0 <= new_y && new_y < w){
                if(maze[x][y] == maze[new_x][new_y] && maze[(x+new_x)/2][(y+new_y)/2] < maze[x][y] && !seen[new_x][new_y]){
                    q.push(P(new_x,new_y));
                }
            }
        }
    }
    cout << (seen[gx][gy] ? "YES" : "NO") << endl;
    return 0;
}