#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <climits>
#include <cmath>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <functional>
#include <set>
#include <numeric>
#include <stack>
#include <utility>
#include <time.h>
#include <iterator>
//#include "util.h"

using namespace std;
typedef unsigned uint;
typedef long long lint;
typedef unsigned long long ulint;



//呪文
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const pair<_KTy, _Ty>& m) { cout << "{" << m.first << ", " << m.second << "}"; return ostr; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const map<_KTy, _Ty>& m) { if (m.empty()) { cout << "{ }"; return ostr;	} cout << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { cout << ", " << *itr; } cout << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const vector<_Ty>& v) { if (v.empty()) { cout << "{ }"; return ostr; }	cout << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { cout << ", " << *itr; }	cout << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const set<_Ty>& s) { if (s.empty()) { cout << "{ }"; return ostr; } cout << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { cout << ", " << *itr; }	cout << "}"; return ostr; }
template <typename T> void print(T* v, int N) { if (N == 0) cout << "{ }"; cout << "{" << v[0]; for (int i = 1; i < N; i++) cout << ", " << v[i]; cout << "}"; }
#define PI 3.14159265358979323846
#define EPS 1e-8
#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))
#define all(x) (x).begin(), (x).end()



typedef pair<int, int> pii;

const int dx[] = { 1, 0, -1, 0 };
const int dy[] = { 0, -1, 0, 1 };

int yuki0424()
{
	int h, w;
	cin >> h >> w;

	int sx, sy, gx, gy;
	cin >> sx >> sy >> gx >> gy;

	pii s = pii(sx - 1, sy - 1), g = pii(gx - 1, gy - 1);

	vector<string> mp(h);
	for (int i = 0; i < h; i++) cin >> mp[i];

	queue<pii> qu;
	qu.push(s);

	while (!qu.empty()) {
		pii t = qu.front();
		if (t == g) {
			cout << "YES" << endl;
			return 0;
		}

		qu.pop();

		int x = t.first;
		int y = t.second;
		int c = mp[x][y];

		// 移動済み
		mp[x][y] = '.';

		// 移動可能座標をキューに入れる
		for (int d = 0; d < 4; d++) {
			int nx = x + dx[d];
			int ny = y + dy[d];
			if (nx < 0 || h <= nx || ny < 0 || w <= ny || mp[nx][ny] == '.') continue;
			int nc = mp[nx][ny];

			// 段差が 1 以内
			if (abs(c - nc) <= 1)
				qu.push(pii(nx, ny));

			nx = x + 2 * dx[d];
			ny = y + 2 * dy[d];
			if (nx < 0 || h <= nx || ny < 0 || w <= ny || mp[nx][ny] == '.') continue;
			int nnc = mp[nx][ny];

			// 2 個先にはしごをかけられる
			if (c == nnc && nc < c)
				qu.push(pii(nx, ny));
		}
	}

	cout << "NO" << endl;

	return 0;
}

int main()
{
	//clock_t start, end;
	//start = clock();

	yuki0424();
	
	//end = clock();
	//printf("%d msec.\n", end - start);

	return 0;
}