#include <bits/stdc++.h>
using namespace std;

#define int long long

#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint,int> P1;
typedef pair<int,pint> P2;
typedef pair<pint,pint>PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD=1000000007;
const ll INF=1e18;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};

int H,W;
int sy,sx,gy,gx;
string s[55];
int can[55][55]={};

void f(int p,int q){
    if(!can[p][q]){
        can[p][q]++;
        if(p>0&&abs(s[p-1][q]-s[p][q])<2)f(p-1,q);
        if(p<H-1&&abs(s[p+1][q]-s[p][q])<2)f(p+1,q);
        if(q>0&&abs(s[p][q-1]-s[p][q])<2)f(p,q-1);
        if(q<W-1&&abs(s[p][q+1]-s[p][q])<2)f(p,q+1);
        if(p>1&&s[p-2][q]==s[p][q]&&s[p][q]>s[p-1][q])f(p-2,q);
        if(p<H-2&&s[p+2][q]==s[p][q]&&s[p][q]>s[p+1][q])f(p+2,q);
        if(q>1&&s[p][q-2]==s[p][q]&&s[p][q]>s[p][q-1])f(p,q-2);
        if(q<W-2&&s[p][q+2]==s[p][q]&&s[p][q]>s[p][q+1])f(p,q+2);
    }
}

signed main(){
    cin.tie(0);
	ios::sync_with_stdio(false);
    cin>>H>>W;
    cin>>sx>>sy>>gx>>gy;
    sx--;sy--;gx--;gy--;
    rep(i,0,H){
        cin>>s[i];
    }
    f(sx,sy);
    puts(can[gx][gy]?"YES":"NO");
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    return 0;
}