#include <bits/stdc++.h>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

ll gcd(ll n, ll m)
{
	ll tmp;
	while (m != 0)
	{
		tmp = n % m;
		n = m;
		m = tmp;
	}
	return n;
}

ll lcm(ll n, ll m)
{
	return abs(n) / gcd(n, m) * abs(m); //gl=xy
}

using namespace std;

vector<vector<int>> grid_bfs(int h,int w,int x,int y,vector<string> &maze,char obstacle='#') {
  const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };//4方向移動
  const int init=1e7;
  vector<vector<int>>d(h,vector<int>(w,init));
  d[x][y]=0;
  queue<pair<int, int>>q;
	pair<int, int>p;
  q.emplace(x,y);
	while (!q.empty()) {
		p = q.front();
		q.pop();
		for (int i = 0; i < 4; ++i) {
			int nx = p.first+dx[i]; int ny = p.second+dy[i];
			if (0 <= nx && nx < h && 0 <= ny && ny < w && maze[nx][ny] != obstacle && d[nx][ny] == init) {
				if(abs(maze[nx][ny]-maze[p.first][p.second])>1)continue;
				q.push(make_pair(nx, ny));
				d[nx][ny] = d[p.first][p.second] + 1;
			}
		}
		for (int i = 0; i < 4; ++i) {
			int nx = p.first+dx[i]*2; int ny = p.second+dy[i]*2;
			if (0 <= nx && nx < h && 0 <= ny && ny < w && maze[nx][ny] != obstacle && d[nx][ny] == init) {
				if(abs(maze[nx][ny]-maze[p.first][p.second])>0)continue;
				q.push(make_pair(nx, ny));
				d[nx][ny] = d[p.first][p.second] + 1;
			}
		}
	}
  return d;//initを含むことに注意
}

void solve()
{
	int h,w;
	cin>>h>>w;
	int sx,sy,gx,gy;
	cin>>sx>>sy>>gx>>gy;
	sx--;sy--;gx--;gy--;
	vector<string>s(h);
	rep(i,h)cin>>s[i];
	auto d=grid_bfs(h,w,sx,sy,s);
	if(d[gx][gy]==1e7){
		cout<<"NO\n";
	}
	else cout<<"YES\n";
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}