#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

struct UnionFind {
	vector<int> data;
	void init(int n) { data.assign(n, -1); }
	bool unionSet(int x, int y) {
		x = root(x); y = root(y);
		if(x != y) {
			if(data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
		}
		return x != y;
	}
	bool findSet(int x, int y) { return root(x) == root(y); }
	int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
	int size(int x) { return -data[root(x)]; }
};

int main() {
	int h; int w;
	while(~scanf("%d%d", &h, &w)) {
		int sy; int sx; int gy; int gx;
		scanf("%d%d%d%d", &sy, &sx, &gy, &gx), -- sy, -- sx, -- gy, -- gx;
		vector<string> b(h);
		rep(i, h) {
			char buf[51];
			scanf("%s", buf);
			b[i] = buf;
		}
		UnionFind uf; uf.init(h * w);
		rep(i, h) rep(j, w) {
			static const int dy[4] = { 0, 1, 0, -1 }, dx[4] = { 1, 0, -1, 0 };
			for(int d = 0; d < 4; ++ d) {
				int yy = i + dy[d], xx = j + dx[d];
				if(yy < 0 || yy >= h || xx < 0 || xx >= w) continue;
				if(abs(b[yy][xx] - b[i][j]) <= 1) {
					uf.unionSet(i * w + j, yy * w + xx);
				} else if(b[yy][xx] < b[i][j]) {
					int yyy = yy + dy[d], xxx = xx + dx[d];
					if(yyy < 0 || yyy >= h || xxx < 0 || xxx >= w) continue;
					if(b[yyy][xxx] == b[i][j])
						uf.unionSet(i * w + j, yyy * w + xxx);
				}

			}
		}
		bool ans = uf.findSet(sy * w + sx, gy * w + gx);
		puts(ans ? "YES" : "NO");
	}
	return 0;
}