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

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> veci;
typedef vector<ll> vecll;
typedef vector<string> vecs;
template<class T,class U> using Hash=unordered_map<T,U>;
 
#define REP(i, a, n) for(ll i = a; i < (ll)(n); i++)
#define RREP(i, a, n) for(ll i = n-1; i >= (ll)(a); i--)
#define rep(i, n) REP(i, 0, n)
#define rrep(i, n) RREP(i, 0, n)
#define MD 1000000007
#define _SPLIT " "
 
template<class T> T read(){T a;cin >> a;return a;}
template<class T> void read(T& a){cin >> a;}
template<class T,class ...Args> void read(T& a, Args&... args){cin >> a; read(args...);} 
template<class T> void rarr(T a, int n){for(int i = 0; i < n; i++) {cin >> a[i];}}
template<class T> void write(T a){cout << setprecision(12) << a << endl;}
template<class T,class ...Args> void write(T a, Args... args){cout << setprecision(12) << a << _SPLIT; write(args...);}
template<class T> void warr(vector<T> a, const char* c = " "){cout << a[0];for(int i = 1; i < (int)a.size(); i++)cout << c << a[i];cout << endl;;}
template<class T> void warr(T a, int n, const char* c = " "){cout << a[0];for(int i = 1; i < n; i++)cout << c << a[i];cout << endl;}
void split(string s, string delim, veci& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(atoi(s.substr(pos).data()));break;}else {result.push_back(atoi(s.substr(pos, p - pos).data()));}pos = p + delim.size();}}
void split(string s, string delim, vecs& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(s.substr(pos));break;}else {result.push_back(s.substr(pos, p - pos));}pos = p + delim.size();}}
ll gcd(ll a, ll b){while(true){ll k = a % b;if(k == 0)return b;a = b;b = k;}}
ll comb(ll n, ll m){ll p=1;m=min(m,n-m);for(ll i=1;i<=m;i++){p*=n-i+1;p/=i;}return p;}

struct Info{
    int x,y;
};

int main(void)
{
    int h,w,sx,sy,gx,gy;
    read(h,w,sy,sx,gy,gx);
    sx--;sy--;gx--;gy--;
    string f[50];
    int dx[]={1,0,-1,0};
    int dy[]={0,1,0,-1};
    rarr(f,h);
    queue<Info> q;
    bool vis[50][50]={0};
    q.push({sx,sy});
    vis[sy][sx]=true;
    while(!q.empty()){
        auto tp=q.front();
        q.pop();
        if(tp.x==gx&&tp.y==gy){
            write("YES");
            return 0;
        }
        char cf=f[tp.y][tp.x];
        rep(i,4){
            int cx1=tp.x+dx[i];
            int cy1=tp.y+dy[i];
            int cx2=tp.x+dx[i]*2;
            int cy2=tp.y+dy[i]*2;
            if(cx1>=0&&cx1<w&&cy1>=0&&cy1<h&&!vis[cy1][cx1]){
                int d=abs(cf-f[cy1][cx1]);
                if(d<=1)q.push({cx1,cy1}),vis[cy1][cx1]=true;
            }
            if(cx2>=0&&cx2<w&&cy2>=0&&cy2<h&&!vis[cy2][cx2]){
                if(cf>f[cy1][cx1]&&cf==f[cy2][cx2])q.push({cx2,cy2}),vis[cy2][cx2]=true;
            }
        }
    }
    write("NO");
    return 0;
}