#ifdef LOCAL111
#else
	#define NDEBUG
#endif
#include <bits/stdc++.h>
const int INF = 1e8;
using namespace std;

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define RBP(i,a) for(auto& i : a)
#ifdef LOCAL111
	#define DEBUG(x) cout<<#x<<": "<<(x)<<endl
	template<typename T> void dpite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
#else
	#define DEBUG(x) true
	template<typename T> void dpite(T a, T b){ return; }
#endif
#define F first
#define S second
#define SNP string::npos
#define WRC(hoge) cout << "Case #" << (hoge)+1 << ": "
#define rangej(a,b,c) ((a) <= (c) and (c) < (b))
#define rrangej(b,c) rangej(0,b,c)
template<typename T> void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}

typedef long long int LL;
typedef unsigned long long ULL;
typedef pair<int,int> P;
typedef pair<LL,LL> LP;

void ios_init(){
	//cout.setf(ios::fixed);
	//cout.precision(12);
#ifdef LOCAL111
	return;
#endif
	ios::sync_with_stdio(false); cin.tie(0);	
}

int dx[] = {0,-1,0,1};
int dy[] = {1,0,-1,0};
int h,w;
bool judge(int x, int y){
	return (0 <= x and x < h and 0 <= y and y < w);
}

int main()
{
	ios_init();
	while(cin >> h >> w){
		int sx, sy, gx, gy;
		cin >> sx >> sy >> gx >> gy;
		sx--; gx--; gy--; sy--;
		vector<string> b(h);
		REP(i,h) cin >> b[i];
		vector<vector<int>> f(h,vector<int>(w,-1));
		function<bool(int,int)> dfs = [&](int x,int y)->bool{
			if(f[x][y] != -1) return f[x][y];
			if(gx == x and gy == y) return f[x][y] = true;
			f[x][y] = false;
			REP(d,4){
				int nx = x+dx[d], ny = y+dy[d];
				if(judge(nx, ny)){
					if(abs(b[nx][ny]-b[x][y]) <= 1){
						// DEBUG(nx); DEBUG(ny);
						f[x][y] |= dfs(nx,ny);
					}
				}
				int nnx = nx+dx[d], nny = ny+dy[d];
				if(judge(nnx, nny)){
					if(b[x][y] == b[nnx][nny] and b[nnx][nny] > b[nx][ny]){
						f[x][y] |= dfs(nnx, nny);
					}
				}
			}
			return f[x][y];
		};
		if(dfs(sx, sy)) cout << "YES" << endl;
		else cout << "NO" << endl;
	}
	return 0;
}