#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#define p(s) cout<<(s)<<endl
#define REP(i,n,N) for(int i=n;i<N;i++)
#define RREP(i,n,N) for(int i=N-1;i>=n;i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
typedef long long ll;
using namespace std;
const ll mod = 1e9+7;

int H, W;
int sx, sy, gx, gy;
string field[55];
bool used[55][55];
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};
int main() {
    cin>>H>>W;
    cin>>sy>>sx>>gy>>gx;
    sx--;sy--;gx--;gy--;
    REP(i,0,H){
        cin>>field[i];
    }
    queue<pair<int, int>> q; //y, x
    q.push({sy, sx});
    while(!q.empty()){
        auto now=q.front();
        //cout<<now.F<<" "<<now.S<<endl;
        if(now.F==gy&&now.S==gx){
            p("YES");
            return 0;
        }
        q.pop();
        REP(k,0,4){
            int nexty = now.F + dy[k];
            int nextx = now.S + dx[k];
            if(!CK(nexty,0,H)||!CK(nextx,0,W)) continue;
            if(used[nexty][nextx]||abs(field[nexty][nextx]-field[now.F][now.S])>1) continue;
            used[nexty][nextx] = true;
            q.push({nexty, nextx});
        }
        REP(k,0,4){
            int nexty = now.F + dy[k]*2;
            int nextx = now.S + dx[k]*2;
            if(!CK(nexty,0,H)||!CK(nextx,0,W)) continue;
            if(used[nexty][nextx]||field[nexty][nextx]!=field[now.F][now.S]) continue;
            if(field[nexty-dy[k]][nextx-dx[k]]>field[now.F][now.S]) continue;
            used[nexty][nextx] = true;
            q.push({nexty, nextx});
        }
    }
    p("NO");
    return 0;
}